Diesel exhaust particle extract elicits an oxPAPC-like transcriptomic profile in macrophages across multiple mouse strains.

Air pollution is a prominent cause of cardiopulmonary illness, but uncertainties remain regarding the mechanisms mediating those effects as well as individual susceptibility. Macrophages are highly responsive to particles, and we hypothesized that their responses would be dependent on their genetic backgrounds. We conducted a genome-wide analysis of peritoneal macrophages harvested from 24 inbred strains of mice from the Hybrid Mouse Diversity Panel (HMDP). Cells were treated with a DEP methanol extract (DEPe) to elucidate potential mechanisms that mediate acute responses to air pollution exposures. This analysis showed that 1,247 genes were upregulated and 1,383 genes were downregulated with DEPe treatment across strains. Pathway analysis identified oxidative stress responses among the most prominent upregulated pathways; indeed, many of the upregulated genes included antioxidants such as Hmox1, Txnrd1, Srxn1, and Gclm, with NRF2 (official gene symbol: Nfe2l2) being the most significant driver. DEPe induced a Mox-like transcriptomic profile, a macrophage subtype typically induced by oxidized phospholipids and likely dependent on NRF2 expression. Analysis of individual strains revealed consistency of overall responses to DEPe and yet differences in the degree of Mox-like polarization across the various strains, indicating DEPe x genetic interactions. These results suggest a role for macrophage polarization in the cardiopulmonary toxicity induced by air pollution.

Perfil molecular de cáncer de endometrio en mujeres de Bogotá D.C., Colombia

Introducción: El cáncer de endometrio ocupa el sexto lugar en incidencia del cáncer en mujeres. La caracterización molecular de este cáncer permite optimizar la estratificación de riesgo para mejorar el tratamiento de las pacientes. Objetivo: Determinar el perfil molecular TCGA de pacientes con cáncer de endometrio en Bogotá, D.C., Colombia. Método: Estudio descriptivo en una cohorte de pacientes con cáncer de endometrio. Las mutaciones en los exones 9 a 14 del gen POLE fueron identificadas mediante amplificación por reacción en cadena de la polimerasa, seguida de secuenciación Sanger y análisis bioinformático. La expresión de las proteínas MMR y p53 se identificó mediante inmunohistoquímica. Resultados: Se incluyeron 40 pacientes con una mediana de edad de 66 años. El 15% presentaron mutaciones en el dominio exonucleasa de POLE. El 32% de las pacientes que no presentaron mutaciones manifestaron deficiencia en el sistema MMR. El 43,47% de las pacientes sin mutaciones en POLE ni alteración del sistema MMR presentaron alteración de la proteína p53. Conclusiones: La población de cáncer de endometrio analizada presenta un perfil molecular TCGA similar a lo reportado para otras poblaciones.

Introduction: Endometrial cancer ranks sixth in cancer incidence among women. Its molecular characterization allows for a more precise risk stratification with the aim of improving patient treatment. Objective: To determine the TCGA molecular profile of patients with endometrial cancer in Bogota, Colombia. Method: A descriptive study of a cohort of patients with endometrial cancer. The expression of MMR proteins and p53 was identified through immunohistochemistry. Mutations in exons 9 to 14 of the POLE gene were identified through polymerase chain reaction amplification, followed by Sanger sequencing and bioinformatic analysis. Results: Forty patients were included in the study, with a median age of 66 years, 15% of them exhibited mutations in the exonuclease domain of POLE, while 32% of patients without mutations showed deficiency in the MMR system. Forty three percent of patients without mutations in POLE or MMR alterations showed aberrant p53 protein expression. Conclusions: The analyzed population of endometrial cancer presents a TCGA molecular profile similar to that reported for other populations.

Impact of hydrocolloid dressings in the prevention of pressure ulcers in high-risk patients: a randomized controlled trial (PENFUP).

It is uncertain whether hydrocolloid dressings, a more costly intervention than offering standard care with petrolatum, is superior to prevent pressure ulcers among hospitalized high-risk adults. Randomized, parallel-group, open-label, superiority trial with an active control group, blinded for investigators, event validators, and analysts (December 1, 2015 to December 12, 2017). Eligible patients were ≥ 18 years of age with intact skin judged as high-risk for skin ulcers (Braden scale), admitted to surgical or medical wards of two tertiary-level hospitals. Participants were randomized (1:1) to protection with hydrocolloid dressings or petrolatum. The primary outcome was the first occurrence of pressure ulcers (with post-injury photographs adjudicated by three judges) under intention-to-treat analysis. Based on prior cost analysis, and the available resources (assumed incidence of 6 ulcers/1000 patient-days in controls), inclusion of up to 1500 participants allowed to surpass a one-sided superiority threshold > 5% based on a target efficacy > 40% for dressings. We planned an economic analysis using a decision tree model based on the effectiveness of the study results from a perspective of the third payer of health care. After inclusion of 689 patients (69 events), the trial was stopped for futility after a planned interim analysis (conditional power < 0.1 for all scenarios if the trial was completed). Pressure ulcers had occurred in 34 (10.2%) patients in the intervention group [9.6 per 1000 patient-days] and 35 (9.9%) participants in the control group [7.9 per 1000 patient-days], HR = 1.07 [95% CI 0.67 to 1.71]. The estimated incremental cost for dressings (a dominated strategy) was USD 52.11 per patient. Using hydrocolloid dressings was found similar to petrolatum for preventing pressure ulcers among hospitalized high-risk patients. As it conveys additional costs, and in this study was unlikely to demonstrate enough superiority, this strategy did not overcome conventional skin care.Trial registration: ClinicalTrials.gov identifier (NCT number): NCT02565745 registered on December 1, 2015.

Single Nucleotide Variants in the TLR1, TLR2 and TLR6 Genes: A Case-Control Study in a Colombian Population.

BACKGROUND: Single nucleotide variants in toll-like receptor genes play a crucial role in leprosy susceptibility or resistance. METHODS: With an epidemiology case-control study, associations between SNVs rs5743618 in TLR1, rs5743708 in TLR2, and rs5743810 in TLR6 and overall susceptibility for leprosy were estimated in 114 cases and 456 controls. Following that, stratified analysis was performed. DNA was extracted from peripheral blood. Genotyping was performed using predesigned TaqMan probes. RESULTS: The A/G genotype of rs5743810 behaved as a protective factor for the development of leprosy in the codominant (OR= 0.37; 95% CI = 016-0.86, p = 0.049) and over-dominant (OR = 0.38; 95% CI = 0.16-0.88, p = 0.019) inheritance models. The A/G and A/A genotypes behaved as a protective factor (OR = 0.39; 95% CI = 0.17-0.87, p = 0.016) in the dominant model. The SNVs rs5743618 and rs5743708 showed no association with any of the models. The CGG haplotype (rs5743618-rs5743708-rs5743810) behaved as a susceptibility factor for developing leprosy (OR = 1.86; 95% CI = 1.11-3.10, p = 0.019). The latter haplotype behaved as a susceptibility factor for leprosy development in women (OR = 2.39; 95% CI = 1.21-4.82, p = 0.013). CONCLUSIONS: The identified variants in the genes encoding TLRs, specifically rs5743810 in TLR6 and CGG (rs5743618-rs5743708-rs5743810) haplotypes, may somehow explain leprosy susceptibility in the studied population in a leprosy endemic region in Colombia.

Integration of human stem cell-derived in vitro systems and mouse preclinical models identifies complex pathophysiologic mechanisms in retinal dystrophy.

Rare DRAM2 coding variants cause retinal dystrophy with early macular involvement via unknown mechanisms. We found that DRAM2 is ubiquitously expressed in the human eye and expression changes were observed in eyes with more common maculopathy such as Age-related Macular Degeneration (AMD). To gain insights into pathogenicity of DRAM2-related retinopathy, we used a combination of in vitro and in vivo models. We found that DRAM2 loss in human pluripotent stem cell (hPSC)-derived retinal organoids caused the presence of additional mesenchymal cells. Interestingly, Dram2 loss in mice also caused increased proliferation of cells from the choroid in vitro and exacerbated choroidal neovascular lesions in vivo. Furthermore, we observed that DRAM2 loss in human retinal pigment epithelial (RPE) cells resulted in increased susceptibility to stress-induced cell death in vitro and that Dram2 loss in mice caused age-related photoreceptor degeneration. This highlights the complexity of DRAM2 function, as its loss in choroidal cells provided a proliferative advantage, whereas its loss in post-mitotic cells, such as photoreceptor and RPE cells, increased degeneration susceptibility. Different models such as human pluripotent stem cell-derived systems and mice can be leveraged to study and model human retinal dystrophies; however, cell type and species-specific expression must be taken into account when selecting relevant systems.

Recombinant human TIM-3 ectodomain expressed in bacteria and recovered from inclusion bodies as a stable and active molecule.

Introduction: Microbial systems, such as Escherichia coli, as host recombinant expression is the most versatile and the cheapest system for protein production, however, several obstacles still remain, such as recovery of soluble and functional proteins from inclusion bodies, elimination of lipopolysaccharides (LPS) contamination, incomplete synthesis, degradation by proteases, and the lack of post-translational modifications, which becomes even more complex when comes to membrane proteins, because they are difficult not only to produce but also to keep in solution in its active state. T-cell Immunoglobulin and Mucin domain 3 (TIM-3) is a type I transmembrane protein that is predominantly expressed on the surface of T lymphocytes, natural killer (NK) cells, dendritic cells, and macrophages, playing a role as a negative immune checkpoint receptor. TIM-3 comprises a single ectodomain for interaction with immune system soluble and cellular components, a transmembrane domain, and a cytoplasmic tail, responsible for the binding of signaling and scaffolding molecules. TIM-3 pathway holds potential as a therapeutic target for immunotherapy against tumors, autoimmunity, chronic virus infections, and various malignancies, however, many aspects of the biology of this receptor are still incompletely understood, especially regarding its ligands. Methods: Here we overcome, for the first time, the challenge of the production of active immune checkpoint protein recovered from bacterial cytoplasmic inclusion bodies, being able to obtain an active, and non-glycosylated TIM-3 ectodomain (TIM-3-ECD), which can be used as a tool to better understand the interactions and roles of this immune checkpoint. The TIM-3 refolding was obtained by the association of high pressure and alkaline pH. Results: The purified TIM-3-ECD showed the correct secondary structure and was recognized from anti-TIM-3 structural-dependent antibodies likewise commercial TIM-3-ECD was produced by a mammal cells system. Furthermore, immunofluorescence showed the ability of TIM-3-ECD to bind to the surface of lung cancer A549 cells and to provide an additional boost for the expression of the lymphocyte activation marker CD69 in anti-CD3/CD28 activated human PBMC. Discussion: Taken together these results validated a methodology able to obtain active checkpoint proteins from bacterial inclusion bodies, which will be helpful to further investigate the interactions of this and others not yet explored immune checkpoints.

Medium-chain fatty acids modify macrophage expression of metabolic and inflammatory genes in a PPAR ß/δ-dependent manner.

There is great interest on medium chain fatty acids (MCFA) for cardiovascular health. We explored the effects of MCFA on the expression of lipid metabolism and inflammatory genes in macrophages, and the extent to which they were mediated by the nuclear receptor peroxisome proliferator-activated receptor beta/delta (PPAR ß/δ). J774A.1 murine macrophages were exposed to octanoate or decanoate as MCFA, a long-chain fatty acid control (palmitate), or the PPAR ß/δ agonist GW501516, with or without lipopolysaccharide (LPS) stimulation, and with or without an siRNA-induced knockdown of PPAR ß/δ. MCFA increased the expression of Plin2, encoding a lipid-droplet associated protein with anti-inflammatory effects in macrophages, in a partially PPAR ß/δ-dependent manner. Both MCFA stimulated expression of the cholesterol efflux pump ABCA1, more pronouncedly under LPS stimulation and in the absence of PPAR ß/δ. Octanoate stimulated the expression of Pltp, encoding a phospholipid transfer protein that aids ABCA1 in cellular lipid efflux. Only palmitate increased expression of the proinflammatory genes Il6, Tnf, Nos2 and Mmp9. Non-stimulated macrophages exposed to MCFA showed less internalization of fluorescently labeled lipoproteins. MCFA influenced the transcriptional responses of macrophages favoring cholesterol efflux and a less inflammatory response compared to palmitate. These effects were partially mediated by PPAR ß/δ.

A systems biology approach uncovers novel disease mechanisms in age-related macular degeneration.

Age-related macular degeneration (AMD) is a leading cause of blindness, affecting 200 million people worldwide. To identify genes that could be targeted for treatment, we created a molecular atlas at different stages of AMD. Our resource is comprised of RNA sequencing (RNA-seq) and DNA methylation microarrays from bulk macular retinal pigment epithelium (RPE)/choroid of clinically phenotyped normal and AMD donor eyes (n = 85), single-nucleus RNA-seq (164,399 cells), and single-nucleus assay for transposase-accessible chromatin (ATAC)-seq (125,822 cells) from the retina, RPE, and choroid of 6 AMD and 7 control donors. We identified 23 genome-wide significant loci differentially methylated in AMD, over 1,000 differentially expressed genes across different disease stages, and an AMD Müller state distinct from normal or gliosis. Chromatin accessibility peaks in genome-wide association study (GWAS) loci revealed putative causal genes for AMD, including HTRA1 and C6orf223. Our systems biology approach uncovered molecular mechanisms underlying AMD, including regulators of WNT signaling, FRZB and TLE2, as mechanistic players in disease.

Complete Genome Assembly and Annotation of Escherichia coli Bacteriophage 55 from Rivière la Quint in Gonaïves, Haiti.

We present the structural and functional annotation of Escherichia coli bacteriophage 55, which has a genome length of 170,393 bp, with 219 predicted genes.

Postweaning cafeteria diet induces a short-term metabolic disfunction and a differential vulnerability to develop anxiety-like and depressive-like behaviors in male but not female rats.

Children and adolescents are high consumers of Western diets (rich in fat and sugars), which is a risk factor for overweight and obesity. Moreover, the presence of anxiety and depression among this population has increased significantly. This study explores in young postweaning rats the association between Western diet consumption and the development of metabolic and behavioral disturbances. At postnatal day (PN) 24, Wistar rats of both sexes were weaned and assigned to a control or cafeteria diet (CAF) group. After short-term exposure, a group of rats was euthanized at PN31 to obtain abdominal fat pads and blood samples. Another group of rats was tested in the open-field test, splash test, anhedonia test, and social play across 11 days (PN32-42). The CAF groups exhibited a significantly high level of body fat, serum glucose, triglycerides, leptin, and HOMA index when compared to the control groups. Only CAF males exhibited anxiety-like and depression-like behavior. Present results indicate that postweaning short-term exposure to a CAF diet has immediate detrimental effects on metabolism in both sexes. However, only CAF males showed mood disturbances. This study provides evidence that a CAF diet exerts immediate effects on behavior and metabolism in the postweaning period and that sexes present differential vulnerability.

Consumption of Sugary Drinks among Urban Adults in Colombia: Association with Sociodemographic Factors and Body Adiposity.

INTRODUCTION: Calories from sugar-sweetened beverages (SSBs) contribute to the development of noncommunicable diseases. There is limited knowledge of the intake of SSBs and their correlates in developing countries. Thus, this study aimed to estimate the consumption of multiple SSBs and their sociodemographic correlates in an urban adult population from Colombia, South America. METHODS: This was a probabilistic, population-level study of adults aged 18 to 75 from five cities representing different regions of Colombia. Dietary intake was assessed employing a 157-item semiquantitative food frequency questionnaire that inquired about intake over the last year. The consumption of regular soda, low-calorie soda, homemade and industrialized fruit juices, energy drinks, sport drinks, malt drinks and traditional sugar cane infusion ("agua de panela") was analyzed for the total sample and subgroups defined by sociodemographic and clinical factors of interest. RESULTS: The study included 1491 individuals (female: 54.2%, mean age: 45.3, overweight: 38.0%, obese: 23.3%). Sugary beverages contributed, on average, 287 Cal/d among women and 334 Cal/d among men, representing 8.9% of total daily calories (TDC). Women in the lowest SEL consumed 10.6% of their TDC from sugary drinks, as opposed to 6.6% for those in a high SEL. For men, this difference was not present (p-value for interaction = 0.039). Interestingly, a higher educational level correlated with a lower consumption of calories from sugary drinks only among men. Fruit juices were by far the main source of sugary drinks, and their consumption did not change sizably by sex and socioeconomic or educational level. Among women, there was a negative association between socioeconomic level (SEL) and consumption of regular soda, a 50% difference between extreme levels. The intake of low-calorie soda was much higher among men than women, and it more than tripled in the highest vs. lowest SEL among men. The consumption of energy drinks was heavily concentrated in men of low SEL. CONCLUSION: Colombian urban adults obtain a considerable proportion of their calories from sugary drinks, especially vulnerable groups such as women with lower education. Given the recent acceleration of the obesity epidemic in Latin America, strategies to limit the intake of such liquid calories may provide important public health benefits.

Dose escalation randomised study of efmarodocokin alfa in healthy volunteers and patients with ulcerative colitis.

BACKGROUND: The interleukin-22 cytokine (IL-22) has demonstrated efficacy in preclinical colitis models with non-immunosuppressive mechanism of action. Efmarodocokin alfa (UTTR1147A) is a fusion protein agonist that links IL-22 to the crystallisable fragment (Fc) of human IgG4 for improved pharmacokinetic characteristics, but with a mutation to minimise Fc effector functions. METHODS: This randomised, phase 1b study evaluated the safety, tolerability, pharmacokinetics and pharmacodynamics of repeat intravenous dosing of efmarodocokin alfa in healthy volunteers (HVs; n=32) and patients with ulcerative colitis (n=24) at 30-90 µg/kg doses given once every 2 weeks or monthly (every 4 weeks) for 12 weeks (6:2 active:placebo per cohort). RESULTS: The most common adverse events (AEs) were on-target, reversible, dermatological effects (dry skin, erythema and pruritus). Dose-limiting non-serious dermatological AEs (severe dry skin, erythema, exfoliation and discomfort) were seen at 90 µg/kg once every 2 weeks (HVs, n=2; patients, n=1). Pharmacokinetics were generally dose-proportional across the dose levels, but patients demonstrated lower drug exposures relative to HVs at the same dose. IL-22 serum biomarkers and IL-22-responsive genes in colon biopsies were induced with active treatment, and microbiota composition changed consistent with a reversal in baseline dysbiosis. As a phase 1b study, efficacy endpoints were exploratory only. Clinical response was observed in 7/18 active-treated and 1/6 placebo-treated patients; clinical remission was observed in 5/18 active-treated and 0/6 placebo-treated patients. CONCLUSION: Efmarodocokin alfa had an adequate safety and pharmacokinetic profile in HVs and patients. Biomarker data confirmed IL-22R pathway activation in the colonic epithelium. Results support further investigation of this non-immunosuppressive potential inflammatory bowel disease therapeutic. TRIAL REGISTRATION NUMBER: NCT02749630.

"I left my shyness behind": Sustainable community-led development and processes of motivation among rural Nicaraguan women.

This paper explores motivational changes of Nicaraguan women involved in sustainable community-led development. Sustainability is the goal of many organizations engaged with capacity development interventions. Research on what such sustainability entails point to a correlation between sustained action by communities, postintervention, and high levels of social capital, collective agency, and efficacy. But what factors motivate people to develop the social capital, self-efficacy, and agency that enable them to sustain their actions towards their communities' well-being? Using Self-Determination Theory as framework, and drawing from interview data, this qualitative paper explores the psychosocial processes rural Nicaraguan women undergo when initially engaging in, and eventually committing to community-led projects. Types of motivation in combination with shifts from initial to more sustained forms of motivation, we conclude, can inform current and future community development interventions on the role motivation plays toward establishing agency, efficacy, and relationships-that is, essential components of sustainable community development.

Systems genomics in age-related macular degeneration.

Genomic studies in age-related macular degeneration (AMD) have identified genetic variants that account for the majority of AMD risk. An important next step is to understand the functional consequences and downstream effects of the identified AMD-associated genetic variants. Instrumental for this next step are 'omics' technologies, which enable high-throughput characterization and quantification of biological molecules, and subsequent integration of genomics with these omics datasets, a field referred to as systems genomics. Single cell sequencing studies of the retina and choroid demonstrated that the majority of candidate AMD genes identified through genomic studies are expressed in non-neuronal cells, such as the retinal pigment epithelium (RPE), glia, myeloid and choroidal cells, highlighting that many different retinal and choroidal cell types contribute to the pathogenesis of AMD. Expression quantitative trait locus (eQTL) studies in retinal tissue have identified putative causal genes by demonstrating a genetic overlap between gene regulation and AMD risk. Linking genetic data to complement measurements in the systemic circulation has aided in understanding the effect of AMD-associated genetic variants in the complement system, and supports that protein QTL (pQTL) studies in plasma or serum samples may aid in understanding the effect of genetic variants and pinpointing causal genes in AMD. A recent epigenomic study fine-mapped AMD causal variants by determing regulatory regions in RPE cells differentiated from induced pluripotent stem cells (iPSC-RPE). Another approach that is being employed to pinpoint causal AMD genes is to produce synthetic DNA assemblons representing risk and protective haplotypes, which are then delivered to cellular or animal model systems. Pinpointing causal genes and understanding disease mechanisms is crucial for the next step towards clinical translation. Clinical trials targeting proteins encoded by the AMD-associated genomic loci C3, CFB, CFI, CFH, and ARMS2/HTRA1 are currently ongoing, and a phase III clinical trial for C3 inhibition recently showed a modest reduction of lesion growth in geographic atrophy. The EYERISK consortium recently developed a genetic test for AMD that allows genotyping of common and rare variants in AMD-associated genes. Polygenic risk scores (PRS) were applied to quantify AMD genetic risk, and may aid in predicting AMD progression. In conclusion, genomic studies represent a turning point in our exploration of AMD. The results of those studies now serve as a driving force for several clinical trials. Expanding to omics and systems genomics will further decipher function and causality from the associations that have been reported, and will enable the development of therapies that will lessen the burden of AMD.

Genome Sequences of Elezi, Asa16, and Niobe, Three Cluster AZ Phages Isolated Using Arthrobacter globiformis B-2979.

The Actinobacteriophages Elezi, Asa16, and Niobe infect Arthrobacter globiformis B-2979 and are closely related to Eraser and London in Cluster AZ. They have flexible noncontractile tails, are predicted to be temperate phages, and their genome sizes range between 43,471 bp and 43,602 bp.

Measurement of stigma and associated characteristics in people with tuberculosis in Medellín, Colombia: a cross-sectional study.

BACKGROUND: Stigma towards tuberculosis (TB) delays diagnosis and compromises adherence to treatment. We measured the degree of stigma and identified the sociodemographic and clinical characteristics that were associated with a higher degree of stigma in patients with pulmonary and extrapulmonary TB in Colombia. METHODS: We conducted a cross-sectional study with 232 participants included in the TB control program in 2017. Sociodemographic and clinical variables were measured. The stigma component was measured through a validated scale and a multiple linear regression was used. RESULTS: The study analysed 232 patients, of which 52.2% were men, 53.5% were between 27 and 59 y of age and 66.8% had a basic-medium education level. Two characteristics were significantly related to a higher stigma score: the basic-medium education level and homeless status. Homeless status increased the stigma score by 0.27. In contrast, the adjusted stigma score decreased by 0.07 if the patient's health status was perceived as 'healthy'. CONCLUSION: Stigma is maximized in homeless patients and patients with a low education level. It is minimized in patients who perceive their state of health as 'healthy'.

Structural analysis of mixed α- and ß-amyrin samples.

Little is known about the structure and molecular arrangement of α- and ß-amyrin, a class of triterpenoids found within the cuticle of higher plants. Blends of both amyrin isomers with different ratios have been studied taking into consideration a combined methodology of density functional theory (DFT) calculations with experimental data from scanning electron microscopy, differential scanning calorimetry and Raman vibrational spectroscopy. Results indicate that trigonal trimeric aggregations of isomer mixtures are more stable, especially in the 1 : 2 (α : ß) ratio. A combination of Raman spectroscopy and DFT calculations has allowed to develop an equation to determine the amount of ß-amyrin in a mixed sample.

Perception and Knowledge of Mercury by Occupationally Exposed Health Care Personnel.

Thermometers and baumanometers frequently contain mercury, a toxic heavy metal. Inadequate management of this substance can constitute an occupational hazard by exposing health care professionals to health risks including memory loss, psychosomatic symptoms, fatigue, and other signs of cognitive dysfunction as reported in several studies. PURPOSE: To assess Mexico's health care professionals' health and mercury-related knowledge and risk perception and to explore the measurement properties of a questionnaire assessing that level of knowledge. MATERIALS AND METHODS: Mixed methodology. A quantitative, cross-sectional study was conducted to measure health care professionals' knowledge of mercury and to validate an instrument using a Rasch analysis in 160 professionals. A qualitative study involving in-depth interviews was conducted to identify participants' risk perception for mercury exposure. RESULTS: The total knowledge of mercury was 19.0 ± 2.0 on a scale of 0 to 28 points. The scores for medical specialists were significantly (P < .001) higher, ranging between 20.0 ± 2.05 and 23.0 ± 1.63. In general, the level of risk perception for mercury exposure was low. The questionnaire presented a reasonable fit to the Rasch model (good item fit with a Bonferroni-adjusted P = .000714). The response categories of three items were collapsed, and two pairs of items were bundled into two super items. CONCLUSION: The levels of the knowledge of the health and safety risks and risk perception for mercury exposure in the Mexican health care professionals evaluated were low. Health care professionals should receive comprehensive training in the safe use and health risks of mercury.