Optimal mechanical interactions direct multicellular network formation on elastic substrates.

Cells self-organize into functional, ordered structures during tissue morphogenesis, a process that is evocative of colloidal self-assembly into engineered soft materials. Understanding how intercellular mechanical interactions may drive the formation of ordered and functional multicellular structures is important in developmental biology and tissue engineering. Here, by combining an agent-based model for contractile cells on elastic substrates with endothelial cell culture experiments, we show that substrate deformation-mediated mechanical interactions between cells can cluster and align them into branched networks. Motivated by the structure and function of vasculogenic networks, we predict how measures of network connectivity like percolation probability and fractal dimension as well as local morphological features including junctions, branches, and rings depend on cell contractility and density and on substrate elastic properties including stiffness and compressibility. We predict and confirm with experiments that cell network formation is substrate stiffness dependent, being optimal at intermediate stiffness. We also show the agreement between experimental data and predicted cell cluster types by mapping a combined phase diagram in cell density substrate stiffness. Overall, we show that long-range, mechanical interactions provide an optimal and general strategy for multicellular self-organization, leading to more robust and efficient realizations of space-spanning networks than through just local intercellular interactions.

Twinfilin1 controls lamellipodial protrusive activity and actin turnover during vertebrate gastrulation.

The dynamic control of the actin cytoskeleton is a key aspect of essentially all animal cell movements. Experiments in single migrating cells and in vitro systems have provided an exceptionally deep understanding of actin dynamics. However, we still know relatively little of how these systems are tuned in cell-type-specific ways, for example in the context of collective cell movements that sculpt the early embryo. Here, we provide an analysis of the actin-severing and depolymerization machinery during vertebrate gastrulation, with a focus on Twinfilin1 (Twf1) in Xenopus. We find that Twf1 is essential for convergent extension, and loss of Twf1 results in a disruption of lamellipodial dynamics and polarity. Moreover, Twf1 loss results in a failure to assemble polarized cytoplasmic actin cables, which are essential for convergent extension. These data provide an in vivo complement to our more-extensive understanding of Twf1 action in vitro and provide new links between the core machinery of actin regulation and the specialized cell behaviors of embryonic morphogenesis.

Patterns of pharmaceutical supplies and medicines donations received during a natural disaster.

BACKGROUND: In response to emergencies, such as wildfires, donations of pharmaceuticals often occur. These donations can be given directly by governments, to non-governmental organizations as corporate donations, or by private entities that donate to individual health institutions. OBJECTIVE: This paper aimed to collect, review and analyze pharmaceutical product donations received during the natural disaster caused by wildfires in the San Luis province, Argentina, in September and October 2020. METHODS: A descriptive, cross-sectional, and retrospective study was performed. An introductory approach to good donation practices was also carried out. Medicines were classified and in the case of products that were not suitable for administration, these were discarded. RESULTS: A total of 15,593 units were segregated, of which 52.8% were over-the-counter products and 47.2% were prescription drugs. 86.3% (13,467 units) were accepted, while 13.7% (2126 units) had to be destroyed. The value of donations totaled USD 16,544. The analysis of the results showed that an important part of the donations was irrelevant in the emergency context. Donations were also received in incorrect amounts, which generated a large stock of medicines that couldn't be used. In emergencies, inappropriate donations create additional work during sorting, storage, and distribution, increasing the time professionals need to complete tasks. This extra work can easily overwhelm limited human and logistical resources. CONCLUSIONS: It is important to previously evaluate the real need for donations. In addition, the distribution of donations must be done through pre-established systems and policies. Otherwise, unsolicited and unnecessary drug donations become wasteful and should therefore be avoided.

A High-Efficiency Capacitor-Based Battery Equalizer for Electric Vehicles.

Technology in electric vehicles has increased substantially in the past decade. Moreover, it is projected to grow at record highs in the coming years since these vehicles are needed to reduce the contamination related to the transportation sector. One of the essential elements of an electric car is its battery, due to its cost. Batteries comprise parallel and series-connected cell arrangements to meet the power system requirements. Therefore, they require a cell equalizer circuit to preserve their safety and correct operation. These circuits keep a specific variable of all cells, such as the voltage, within a particular range. Within cell equalizers, capacitor-based ones are very common as they have many desirable characteristics of the ideal equalizer. In this work, an equalizer based on the switched-capacitor is proposed. A switch is added to this technology that allows the disconnection of the capacitor from the circuit. In this way, an equalization process can be achieved without excess transfers. Therefore, a more efficient and faster process can be completed. In addition, it allows another equalization variable to be used, such as the state of charge. This paper studies the operation, power design, and controller design of the converter. Moreover, the proposed equalizer was compared to other capacitor-based architectures. Finally, simulation results were presented to validate the theoretical analysis.

Post-COVID cholangiopathy: A narrative review.

Since the spread of the first cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection much progress has been made in understanding the disease process. However, we are still facing the complications of coronavirus disease 19 (COVID-19). Multiple sequelae may appear as a consequence of acute infection. This set of entities called post-COVID-19 syndrome involves a wide variety of new, recurrent or persistent symptoms grouped together as a consequence of the acute disease process. One of those that has attracted the most attention is the liver and bile duct involvement called post-COVID-19 cholangiopathy. This is characterized by elevation of liver markers such as alkaline phosphatase, bilirubin and transaminases as well as alterations in the bile ducts in imaging studies. Thus, a narrative review of the cases reported until the end of 2021 was carried out. From the findings found, we concluded that patients who have had COVID-19 or during the process have required hospitalization should remain under follow-up for at least 6 months by a multidisciplinary team.

Metaheuristic Parameter Identification of Motors Using Dynamic Response Relations.

This article presents the use of the equations of the dynamic response to a step input in metaheuristic algorithm for the parametric estimation of a motor model. The model equations are analyzed, and the relations in steady-state and transient-state are used as delimiters in the search. These relations reduce the number of random parameters in algorithm search and reduce the iterations to find an acceptable result. The tests were implemented in two motors of known parameters to estimate the performance of the modifications in the algorithms. Tests were carried out with three algorithms (Gray Wolf Optimizer, Jaya Algorithm, and Cuckoo Search Algorithm) to prove that the benefits can be extended to various metaheuristics. The search parameters were also varied, and tests were developed with different iterations and populations. The results show an improvement for all the algorithms used, achieving the same error as the original method but with 10 to 50% fewer iterations.

Differences in Expression of IQSEC2 Transcript Isoforms in Male and Female Cases with Loss of Function Variants and Neurodevelopmental Disorder.

Pathogenic hemizygous or heterozygous mutations in the IQSEC2 gene cause X-linked intellectual developmental disorder-1 (XLID1), characterized by a variable phenotype including developmental delay, intellectual disability, epilepsy, hypotonia, autism, microcephaly and stereotypies. It affects both males and females typically through loss of function in males and haploinsufficiency in heterozygous females. Females are generally less affected than males. Two novel unrelated cases, one male and one female, with de novo IQSEC2 variants were detected by trio-based whole exome sequencing. The female case had a previously undescribed frameshift mutation (NM_001111125:c.3300dup; p.Met1101Tyrfs*5), and the male showed an intronic variant in intron 6, with a previously unknown effect (NM_001111125:c.2459+21C>T). IQSEC2 gene expression study revealed that this intronic variant created an alternative donor splicing site and an aberrant product, with the inclusion of 19bp, confirming the pathogenic effect of the intron variant. Moreover, a strong reduction in the expression of the long, but also the short IQSEC2 isoforms, was detected in the male correlating with a more severe phenotype, while the female case showed no decreased expression of the short isoform, and milder effects of the disease. This suggests that the abnormal expression levels of the different IQSEC2 transcripts could be implicated in the severity of disease manifestations.

Chloroquine Induces ROS-mediated Macrophage Migration Inhibitory Factor Secretion and Epithelial to Mesenchymal Transition in ER-positive Breast Cancer Cell Lines.

Breast cancer (BC) is the leading cause of cancer-related death in women in the world. Since tumor cells employ autophagy as a survival pathway, it has been proposed that autophagy inhibition could be beneficial for cancer treatment. There are several onging clinical trials where autophagy is being inhibited (using chloroquine, CQ or hydroxychloroquine, HCQ) along with chemotherapy with promising results. However, there is also in vitro evidence in which autophagy inhibition can induce epithelial to mesenchymal transition (EMT) in cancer cells, indicating that, at least in some cases, this strategy could be detrimental for cancer patients. In this study, we found that the genetic inhibition of autophagy primed cells for EMT by inducing a decrease in E-cadherin protein levels, while CQ treatment decreased E-cadherin levels, induced morphological changes related to EMT, increased EMT-related transcription factor (EMT-TF) expression and migration in estrogen receptor positive (ER +) BC cell lines. Importantly, CQ treatment increased intracellular reactive oxygen species (ROS) which induced the secretion of macrophage migration inhibitory factor (MIF), a pro-inflammatory cytokine related to malignancy. Both ROS production and MIF secretion were responsible for the mesenchymal morphology and increased migratory capacity induced by CQ. Our results indicate that CQ treatment increased malignancy by inducing ROS production, MIF secretion and EMT and suggest that autophagy inhibition in ER + BC patients might have detrimental effects. Our data indicates that a careful selection of patients should be performed in order to determine who will benefit the most from autophagy inhibition with available pharmacological agents for the treatment of breast cancer.

Short-term efficacy of umbilical cord milking in preterm infants: systematic review and meta-analysis.

BACKGROUND: To systematically evaluate short-term efficacy of UCM versus other interventions in preterm infants. METHODS: Six engines were searched until February 2020 for randomized controlled trials (RCTs) assessing UCM versus immediate cord clamping (ICC), delayed cord clamping (DCC), or no intervention. Primary outcomes were overall mortality, intraventricular hemorrhage (IVH), and patent ductus arteriosus (PDA); secondary outcomes were need for blood transfusion, mean blood pressure (MBP), serum hemoglobin (Hb), and ferritin levels. Random-effects meta-analyses were used. RESULTS: Fourteen RCTs (n = 1708) were included. In comparison to ICC, UCM did not decrease mortality (RR 0.5, 95% CI 0.2-1.1), IVH (RR 0.7, 95% CI 0.5-1.0), or PDA (RR 1.0, 95% CI 0.7-1.5). However, UCM reduced need of blood transfusion (RR 0.5, 95% CI 0.3-0.9) and increased MBP (MD 2.5 mm Hg, 95% CI 0.5-4.5), Hb (MD 1.2 g/dL, 95% CI 0.8-1.6), and ferritin (MD 151.4 ng/dL, 95% CI 59.5-243.3). In comparison to DCC, UCM did not reduce mortality, IVH, PDA, or need of blood transfusion but increased MBP (MD 3.7, 95% CI 0.6-6.9) and Hb (MD 0.3, 95% CI -0.2-0.8). Only two RCTs had high risk of bias. CONCLUSIONS: UCM did not decrease short-term clinical outcomes in comparison to ICC or DCC in preterm infants. Intermediate outcomes improved significantly with UCM. IMPACT: In 14 randomized controlled trials (RCTs), umbilical cord milking (UCM) did not reduce mortality, intraventricular hemorrhage, or patent ductus arteriosus compared to immediate (ICC) or delayed cord clamping (DCC). UCM improved mean blood pressure and hemoglobin levels compared to ICC or DCC. In comparison to ICC, UCM reduced the need for blood transfusion. We updated searches until February 2020, stratified by type of control, and performed subgroup analyses. There was low quality of evidence about clinical efficacy of UCM. Most of RCTs had low risk of bias. UCM cannot be recommended as standard of care for preterm infants.

Quantification of the mesh structure of bundled actin filaments.

Biopolymer networks are essential for a wide variety of cellular functions. The biopolymer actin is known to self-assemble into a variety of spatial structures in response to physiological and physical mechanisms. So far, the mechanics of networks of single actin filaments and bundles has previously been described. However, the spatial structure of actin bundles remains poorly understood. Here, we investigate this question by bundling actin filaments with systematically varied concentrations of known physical bundling agents (MgCl2 and PEG) and physiological bundling agents (α-actinin and fascin). We image bundled actin networks with confocal microscopy and perform analysis to describe their mesh size and the nearest-distance distribution, which we call "mesh structure". We find that the mesh size ξ scales universally with actin concentration as ξ ∼ [actin]-1/2. However, the dependence of ξ on the concentration of the bundling agent depends on the agent used. Finally, we find that nearest-distance distributions are best fit by Weibull and Gamma distributions. A complete understanding of the mesh structure of biopolymer networks leads to a more mechanistic understanding of the structure of the cytoskeleton, and can be exploited to design filters with variable porosity for microfluidic devices.

Glycated hemoglobin as a surrogate for evaluating the effectiveness of drugs in diabetes mellitus trials: a systematic review and trial-level meta-analysis.

OBJECTIVE: The objective of this study was to investigate whether glycated hemoglobin (HbA1c) is a valid surrogate for evaluating the effectiveness of antihyperglycemic drugs in diabetes mellitus (DM) trials. METHODS: We conducted a systematic review of placebo-controlled randomized clinical trials (RCTs) evaluating the effect of a treatment on HbA1c (mean difference between groups) and clinical outcomes (relative risk of mortality, myocardial infarction, stroke, heart failure, and/or kidney injury) in patients with DM. Then, we investigated the association between treatment effects on HbA1c and clinical outcomes using regression analysis at the trial level. Lastly, we interpreted the correlation coefficients (R) using the cut-off points suggested by the Institute for Quality and Efficiency in Healthcare (IQWiG). HbA1c was considered a valid surrogate if it demonstrated a strong association: lower limit of the 95 percent confidence interval (95 percent CI) of R greater than or equal to .85. RESULTS: Nineteen RCTs were identified. All studies included adults with type 2 DM. None of the associations evaluated was strong enough to validate HbA1c as a surrogate for any clinical outcome: mortality (R = .34; 95 percent CI -.14 to .69), myocardial infarction (R = .20; -.30 to .61), heart failure (R = .08; -.40 to .53), kidney injury (R = -.04; -.52 to .47), and stroke (R = .81; .54 to .93). CONCLUSIONS: The evidence from multiple placebo-controlled RCTs does not support the use of HbA1c as a surrogate to measure the effectiveness of antihyperglycemic drugs in DM studies.

Polymicrobial Keratitis: Risk Factors, Clinical Characteristics, Bacterial Profile, and Antimicrobial Resistance.

OBJECTIVE: To describe clinical characteristics, complications, and the most prevalent microorganisms causing polymicrobial keratitis and their antibiotic sensitivities. METHODS: A cross-sectional study including a consecutive analysis of patient's records with a diagnosis of bacterial keratitis with a positive culture and antibiogram report were included. Patients were grouped into those having monomicrobial and polymicrobial infection. Features studied included demographic and clinical characteristics, risk factors, Gram stain, cultures, and antibiotic sensitivity. RESULTS: We included 656 patients; in 31.5% more than one microorganism was found. Seven hundred and twenty-three gram-positive bacteria were isolated, and 336 (46.5%) had polymicrobial keratitis. One hundred sixty-one gram-negative bacteria were isolated, and 99 (61.5%) from polymicrobial keratitis. Fourteen (0.60%) patients presented ring infiltrate, and 10 (71.42%) of those patients had polymicrobial keratitis (X2 10.654, P=0.001). Multivariate analysis showed that patients with history of contact lens use (odds ratio [OR] of 1.78, P=0.042), coexistent autoimmune disease (OR 4.64, P=0.03), irregular edges of the infiltrate (OR 2.06, P=0.005), and ring infiltrate (OR 6.034, P=0.005) have a higher risk for developing polymicrobial infection. In the polymicrobial group, gram-positive and gram-negative organisms showed a high sensitivity to Netilmicin. CONCLUSIONS: We found a high incidence of polymicrobial keratitis. Our results suggest that it should be suspected in patients with a history of contact lens use, coexistent autoimmune disease, infiltrates with indistinct edges, and ring infiltrates. Sensitivities to moxifloxacin are lower than those reported in previous studies, but sensitivity to Netilmicin is higher.

Non-Linear Regression Models with Vibration Amplitude Optimization Algorithms in a Microturbine.

Machinery condition monitoring and failure analysis is an engineering problem to pay attention to among all those being studied. Excessive vibration in a rotating system can damage the system and cannot be ignored. One option to prevent vibrations in a system is through preparation for them with a model. The accuracy of the model depends mainly on the type of model and the fitting that is attained. The non-linear model parameters can be complex to fit. Therefore, artificial intelligence is an option for performing this tuning. Within evolutionary computation, there are many optimization and tuning algorithms, the best known being genetic algorithms, but they contain many specific parameters. That is why algorithms such as the gray wolf optimizer (GWO) are alternatives for this tuning. There is a small number of mechanical applications in which the GWO algorithm has been implemented. Therefore, the GWO algorithm was used to fit non-linear regression models for vibration amplitude measurements in the radial direction in relation to the rotational frequency in a gas microturbine without considering temperature effects. RMSE and R2 were used as evaluation criteria. The results showed good agreement concerning the statistical analysis. The 2nd and 4th-order models, and the Gaussian and sinusoidal models, improved the fit. All models evaluated predicted the data with a high coefficient of determination (85-93%); the RMSE was between 0.19 and 0.22 for the worst proposed model. The proposed methodology can be used to optimize the estimated models with statistical tools.

Determination of Plutonium and Uranium Radionuclides in Glacier Ice Samples by MC-ICP-MS.

A radiochemical procedure for the determination of plutonium (Pu) and uranium (U) radionuclides in ice samples by multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS) is presented. Pu and U radionuclides are preconcentrated by coprecipitation and then separated by extraction chromatography. The purified Pu and U fractions are analyzed by MC-ICP-MS. Detection limits of 2 × 10 -3 and 3 × 10-6 mBq kg-1 were achieved for 239Pu and 236U, respectively. Surface ice samples collected from the Gauli glacier (Switzerland) were analyzed by this method. The surface of the Gauli Glacier retains historical records of 239Pu, 240Pu and 236U from the nuclear weapon testing (NWT) period. Pu and U radionuclides were found to be consistent in terms of pattern, showing two peaks possibly related to the two main periods of the NWTs (1954-1958 and 1961-1963). ³H measurements, also released by the NWT, further confirmed the Pu and U results. The 240Pu/239Pu ratio ranged from 0.14 to 0.25, and 236U/ 239Pu ranged from 0.14 to 0.81. The Pu atom ratios ranged within the limits of global fallout in the most intensive period of NWT (1952 to 1962).

Quality and management status of the drinking water supplies in a semiarid region of Northeastern Brazil.

Surface and groundwater resources in the Seridó Region (Brazilian semiarid) were investigated to evaluate their current quality conditions and suitability for domestic use. The water was characterized in terms of physical, chemical, and radiological parameters; including those required by the Brazilian Drinking Water Quality Standard (DWQS). Information about major and trace elements and radiological aspects of the water are reported for the first time. Salinization was confirmed as a key problem in the region, driven natural and anthropogenic. Overall, water has poor organoleptic characteristics. The concentration of most trace elements was below the recommended level, except for uranium and selenium in groundwater. Gross alpha and beta activities higher than the recommended levels were also recorded in several water samples, mostly from the investigated aquifers. In these samples, a detailed radionuclide analysis is required to estimate the effective dose received by the local population. Overall, the results show that water from the investigated region is not suitable for human consumption unless proper treatment is applied. Water requires proper treatment to decrease the content of dissolved salts, toxic elements, and radionuclides responsible for the high gross alpha and beta activities.

Uncovering the dynamic precursors to motor-driven contraction of active gels.

Cells and tissues have the remarkable ability to actively generate the forces required to change their shape. This active mechanical behavior is largely mediated by the actin cytoskeleton, a crosslinked network of actin filaments that is contracted by myosin motors. Experiments and active gel theories have established that the length scale over which gel contraction occurs is governed by a balance between molecular motor activity and crosslink density. By contrast, the dynamics that govern the contractile activity of the cytoskeleton remain poorly understood. Here we investigate the microscopic dynamics of reconstituted actin-myosin networks using simultaneous real-space video microscopy and Fourier-space dynamic light scattering. Light scattering reveals different regimes of microscopic dynamics as a function of sample age. We uncover two dynamical precursors that precede macroscopic gel contraction. One is characterized by a progressive acceleration of stress-induced rearrangements, while the other consists of sudden, heterogeneous rearrangements. Intriguingly, our findings suggest a qualitative analogy between self-driven rupture and collapse of active gels and the delayed rupture of passive gels observed in earlier studies of colloidal gels under external loads.

A Nafion Film Cover to Enhance the Analytical Performance of the CuO/Cu Electrochemical Sensor for Determination of Chemical Oxygen Demand.

We modified and evaluated the performance of a CuO/Cu electrochemical electrode for chemical oxygen demand (COD) determination by covering it with a Nafion (Nf) film. The resulting modified CuONf/Cu electrode sensor was used for the electrochemical determination of COD in river, slaughterhouse and estuarine water samples in order to evaluate its performance for this particular task. It was compared with the CuO/Cu sensor with no Nafion. The main electrochemical characteristics of interest, resistance, sensitivity, accuracy and reproducibility, were assessed by means of Linear Sweep Voltammetry using glucose as a standard. Results of these essays indicate that the procedure used produced smooth and firmly attached Nf films covering the whole copper surface. This sensor was shown to be resistant to interferences and effective in electro-oxidation of a wide range of organic compounds and therefore very useful for COD determination. Using the newly developed CuONf/Cu electrode an analytical linear range of 50 to 1000 mg·L-1 COD, with a detection limit of 2.11 mg·L-1 (n = 6) COD was achieved. The comparison shows that the CuONf/Cu sensor is more appropriate for COD determination than its counterpart with no Nafion.

Evaluation of the Cadmium Accumulation in Tamarillo Cells (Solanum betaceum) by Indirect Electrochemical Detection of Cysteine-Rich Peptides.

Long-term cadmium intake can be very dangerous to human health due to its toxic effects. Although people can be contaminated with this element from different sources, contaminated food is probably the most important one. Foods such as vegetables and fruits can become contaminated with cadmium existing in soils, irrigation water, or chemical fertilizers. Some plants produce an excess of cysteine-rich peptides (CRp) when affected by high concentrations of heavy metals such as cadmium, thus indicating the presence of this type of contamination. Among these plants is tamarillo (Solanum betaceum), which is locally known as "tree tomato". This is a native plant widely consumed in the Ecuadorian Andes because of its abundance, low cost, and high content of vitamin C and fiber. The fact that Solanum betaceum produces CRp upon contamination with heavy metals means that this plant may be able to accumulate heavy metals. If this is the case, the plant can possibly be used as an indicator of metal pollution. The main goals of the present work were to evaluate the possibility of using Solanum betaceum as an indicator of metal contamination in plants and to examine its capability to accumulate metals. Both goals were met by determination of the amounts of CRp produced by Solanum betaceum cells cultivated in vitro in the laboratory under controlled conditions in the presence of different concentrations of cadmium. The CRp determination was carried out by means of electrogeneration of iodine in an iodide solution containing reduced glutathione as a biological thiol model. Solanum betaceum cells were grown in a Murashige and Skoog solution enriched with a 30 g L-1 sugar aqueous solution and 1 mg L-1 2,4-dichlorophenoxyacetic acid. The results of these experiments confirmed the following: (1) CRp production is a function of the amount of cadmium present as a contaminant up to a limiting value after which cell apoptosis occurs; (2) Solanum betaceum accumulates cadmium; (3) the analytical method used is appropriate for CRp determination; and (4) CRp determination is a valid alternative to detect contamination by heavy metals in plants.

Development and Evaluation of Copper Electrodes, Modified with Bimetallic Nanoparticles, to be Used as Sensors of Cysteine-Rich Peptides Synthesized by Tobacco Cells Exposed to Cytotoxic Levels of Cadmium.

We report on two new electrochemical sensors which, coupled to differential pulse voltammetry, constitutes a useful tool for diagnosis of heavy metal pollution. The electrochemical sensors AgHgNf/Cu and the AgBiNf/Cu were obtained by deposition of bimetallic particles of AgHg or AgBi on copper electrodes covered with a Nafion (Nf) film, respectively. Micrographs of the electrode's surface showed evenly scattered bimetallic particles, with an approximate diameter of 150 nm, embedded in the Nafion (Nf) film. In order to test the electrodes, the hydrogen evolution signal according to the Brdicka reaction was measured for the determination of cysteine-rich peptides (CRp) produced by plants. To check the accuracy of the electrodes, real samples of Nicotiana tabacum cells exposed to cytotoxic levels of cadmium were tested. The AgHgNf/Cu electrode produced detection limits (DLs) of 0.088 µmol L-1 for Cysteine and 0.139µmol L-1 for Glutathione, while for the AgBiNf/Cu electrode DLs were 0.41 µmol L-1 for cysteine and 0.244 µmol L-1 for glutathione. Thus, the new electrodes could be a useful analytical electrochemical system very convenient for fieldwork. The electrodes were capable of direct, accurate, and sensitive detection of synthesized peptides, despite the complex matrix where the Nicotiana tabacum cells were grown.

[Suicide risk associated with bullying and depression in high school]. / Riesgo suicida asociado a bullying y depresión en escolares de secundaria.

INTRODUCTION: Suicide risk is increasingly common among children and adolescents. There are no current and local studies of this reality in northern Peru. The objective was to determine whether suici de risk was associated with bullying and depression in high school students. PATIENTS AND METHOD: An analytical cross-sectional study was carried out in a city in northern Peru, using validated surveys to measure suicide risk, bullying and depression. Statical association data were obtained using generali zed linear models. RESULTS: Out of 289 schoolchildren, 20% was at suicide risk and had some type of depression. Among those on the upper tertile of the bullying scale, 38% had suicidal ideation, while those who were depressed, 63% had suicidal ideation. The frequency of suicide risk increased as a result of bullying score (aPR: 1.83, 95% CI: 1.13-2.99, p value = 0.015), being depressed (aPR: 3.32, 95% CI: 1.69-6.51, p value < 0.001), family history of suicide (aPR: 1.99, 95% CI: 1.55-2.56, p va lue < 0.001), the passive desire to die (aPR: 2.20, 95% CI: 1.86-2.61, p value < 0.001), have planned suicide at some point (aPR: 2.05, 95% CI: 1.60-2.64; p value < 0.001) and study in a private school (aPR: 1.16, 95% CI: 1.14-1.18, p value < 0.001); adjusted by gender and school location. Conclu sion: Mental health of schoolchildren was involved in many aspects, several of them associated with a higher frequency of suicide risk.