Ultraviolet-fluorescence detection of E. Coli using threshold-comparison electronics.

We describe an optical system that detects the presence of E. coli bacteria, making use of the bacteria's natural fluorescence properties. The system provides an excitation signal at 365 nm and detects the emission signal, from the bacteria, at approximately 445 nm. The system also allows the intensity of the emitted signal to be compared with a user-programmable threshold. This allows rapid testing of many samples in a laboratory setting. Complete setup and performance details are provided, enabling the experimentalist to tailor the system parameters to other species of microorganisms, which may have fluorescence properties at other wavelengths.

Chemical sensing of common microorganisms found in biopharmaceutical industries using MIR laser spectroscopy and multivariate analysis.

Mid-infrared laser spectroscopy was used to investigate common bacteria encountered in biopharmaceutical industries. The study involved the detection of bacteria using quantum cascade laser spectroscopy coupled to a grazing angle probe (QCL-GAP). Substrates similar to surfaces commonly used in biopharmaceutical industries were used as support media for the samples. Reflectance measurements were assisted by Multivariate Analysis (MVA) to assemble a powerful spectroscopic technique with classification and identification resources. The species analyzed, Staphylococcus aureus, Staphylococcus epidermidis, and Micrococcus luteus, were used to challenge the technique's capability to discriminate from microorganisms of the same family. Principal Components Analysis and Partial Least Squares-Discriminant Analysis differentiated between the bacterial species, using QCL-GAP-MVA as the reference. Spectral differences in the bacterial membrane were used to determine if these microorganisms were present in the samples analyzed. Results herein provided effective discrimination for the bacteria under study with high sensitivity and specificity.

Usability and Feasibility of the Antipsychotic Medication Decision Aid in a Community Program for First-Episode Psychosis.

OBJECTIVE: Although antipsychotic medications are considered first-line treatment for psychosis, rates of discontinuation and nonadherence are high, and debate persists about their use. This pilot study aimed to explore the usability, feasibility, and potential impact of a shared decision making (SDM) intervention, the Antipsychotic Medication Decision Aid (APM-DA), for decisions about use of antipsychotic medications. METHODS: A pilot randomized controlled trial was conducted with 17 participants in a first-episode psychosis program. Nine participants received the APM-DA, and eight received usual care. RESULTS: After their appointments, intervention group participants had less decisional conflict and greater satisfaction with decisions than control group participants had. Use of the APM-DA did not increase appointment length. Comparison of the intervention outcomes with the control outcomes was limited because of the small sample. CONCLUSIONS: The results support the feasibility and usability of an SDM process via the use of the APM-DA in routine community psychosis care.

Alignment and performance analysis of free-space optical communications for broadband video transmission.

We describe a free-space optical communications system operating with an externally modulated infrared carrier signal at 1550 nm. The purpose of the system is to explore an alternative to radio-frequency wireless communications, which are subject to spectral congestion and bandwidth limitations. We provide details of the optical alignment procedure and a means for extrapolating the obtained results to larger transmission distances. To illustrate the versatility of the system, a relatively wideband signal was chosen for transmission: an NTSC analog video signal, whose instantaneous bandwidth was 6 MHz. We describe the performance of the system by examining its output image quality and signal-to-noise ratio.

Clinical and microbiological characterization of Salmonella spp. isolates from patients treated in a university hospital in South America between 2012-2021: a cohort study.

BACKGROUND: Salmonellosis is a major cause of morbidity and mortality and one of the most frequent etiologies of diarrhea in the world. Mortality due to Salmonellosis in Latin America still poorly understood, and there is a lack of studies that evaluate resistance and clinical manifestations. The aims of this study were to characterize patients infected with Salmonella spp. seen in a university hospital in Colombia between 2012 and 2021, to evaluate trends in antibiotic resistance and to determine the proportion of overall mortality and related factors. METHODS: Retrospective observational study. All patients with microbiological diagnosis of Salmonella spp. were included. The sociodemographic, clinical and microbiological characteristics were described, and the proportion of antibiotic resistant isolates per year was estimated. The prevalence of mortality according to age groups was calculated. Log binomial regression models were used to establish factors associated with mortality. RESULTS: Five hundred twenty-two patients were analyzed. Salmonellosis accounted for 0.01% of all medical consultations. The median age was 16 years old. The most common clinical presentation was gastroenteric syndrome (77.1%) and symptoms included diarrhea (79.1%), fever (66.7%), abdominal pain (39.6%) and vomiting (35.2%). Of the Salmonella spp. isolates, 78.2% were not classified, 19.1% corresponded to non-typhoidal Salmonella and 2.7% to Salmonella typhi. Mortality occurs in 4.02% of the patients and was higher in patients with hematologic malignancy (11.6%). When analyzing by age group, the proportion of deaths was 2.8% in patients aged 15 years or younger, while in those older than 15 years it was 5.4%. Factors associated to mortality where bacteremia (aPR = 3.41 CI95%: 1.08-10.76) and to require treatment in the ICU (aPR = 8.13 CI95%: 1.82-37.76). In the last 10 years there has been a steady increase in resistance rates to ciprofloxacin, ampicillin, ampicillin/sulbactam and ceftriaxone, reaching rates above 60% in recent years. CONCLUSIONS: Despite improved availability of antibiotics for the treatment of salmonellosis in the past decades, mortality due to salmonellosis continues occurring in children and adults, mainly in patients with hematological malignancies and bacteremia. Antibiotic resistance rates have increased significantly over the last 10 years. Public health strategies for the control of this disease should be strengthened, especially in vulnerable populations.

Increased incidence of rheumatoid arthritis after COVID-19.

An increase in the incidence of inflammatory arthritis after COVID-19 has been reported. Since many diseases exhibit population-specific causal effect sizes, we aimed to evaluate the incidence trends of inflammatory arthritis, including rheumatoid arthritis (RA), after COVID-19 in a large admixed Colombian population. Data analysis for this retrospective, population-based cohort study was carried out using the COOSALUD EPS registry. The following codes were selected for analyses: M059, seropositive RA, M069, unspecified RA, M060 seronegative RA, and other RA-related diagnoses: M064, M139, M068, M058, M130 and M053. The study period was limited to January 01, 2018, through December 31, 2022. Incidence rates (IRs) and incidence rate ratios (IRRs) were assessed. A Cox survival model was built to evaluate the influence of age, gender, and COVID-19 vaccination status on the development of inflammatory arthritis. A bioinformatic analysis was performed to evaluate the homology between SARS-CoV-2 and autoantigen peptides related to RA. The entire population study comprised 3,335,084 individuals. During the pandemic period (2020-2022) the total IIR for seropositive and unspecified RA were 1.60 (95% CI, 1.16-2.22) and 2.93 (95% CI, 2.04-4.19), respectively, and the IIR for overall RA-related diagnosis was 2.01 (95% CI 1.59-2.53). The age groups hazard ratios (HRs) were increased until the age group of 51-60 years (HR: 9.16; 95% CI, 7.24-11.59) and then decreased slightly in the age group 61 years or older (HR: 5.364; 95% CI, 4.24-6.78) compared to those within 18-30 years. Men were less at risk than women to develop inflammatory arthritis (HR: 0.21; 95% CI, 0.18-0.24). The greater time since COVID-19 diagnosis was associated with a lower likelihood of developing inflammatory arthritis (HR: 0.99; 95% CI:0.998-0.999). Vaccination (all types of COVID-19 vaccines included) did not prevent the development of inflammatory arthritis after COVID-19. Low identity was found between the SARS-CoV-2 ORF1ab antigen and the human antigens Poly ADP-ribose polymerase 14 and Protein mono-ADP-ribosyltransferase PARP9 isoform D (39% and 29%, respectively). In conclusion, our study confirms increased incidence of inflammatory arthritis, including RA, after COVID-19, with the greatest increase occurring before the first year post-covid. Women in their fifties were more susceptible. Further research is required to examine the effectiveness of vaccination in preventing post-COVID inflammatory arthritis and the mechanisms implicated in the development of RA after COVID-19.

Theoretical-Experimental Study of the Action of Trace Amounts of Formaldehyde, Propionaldehyde, and Butyraldehyde as Inhibitors of the Ziegler-Natta Catalyst and the Synthesis of an Ethylene-Propylene Copolymer.

The copolymer synthesis process can be affected by failures in the production process or by contaminating compounds such as ketones, thiols, and gases, among others. These impurities act as an inhibiting agent of the Ziegler-Natta (ZN) catalyst affecting its productivity and disturbing the polymerization reaction. In this work, the effect of formaldehyde, propionaldehyde, and butyraldehyde on the ZN catalyst and the way in which it affects the final properties of the ethylene-propylene copolymer is presented by analyzing 30 samples with different concentrations of the mentioned aldehydes along with three control samples. It was determined that the presence of formaldehyde 26 ppm, propionaldehyde 65.2 ppm, and butyraldehyde 181.2 ppm considerably affect the productivity levels of the ZN catalyst; this effect increases as the concentration of aldehydes is higher in the process; likewise, these impurities affect the properties of the final product, such as the fluidity index (MFI), thermogravimetric analysis (TGA), bending, tension, and impact, which leads to a polymer with low-quality standards and less resistance to breakage. The computational analysis showed that the complexes formed by formaldehyde, propionaldehyde, and butyraldehyde with the active center of the catalyst are more stable than those obtained by the ethylene-Ti and propylene-Ti complexes, presenting values of -40.5, -47.22, -47.5, -5.2 and -1.3 kcal mol-1 respectively.

Disparities in Shared Decision-Making Research and Practice: The Case for Black American Patients.

OBJECTIVE: The extent of shared decision making (SDM) use in the care of Black patients is limited. We explored preferences, needs, and challenges of Black patients to enhance SDM offerings. METHODS: We performed interviews with 32 Black patients receiving type 2 diabetes care in safety-net primary care practices caring predominantly for Black people. RESULTS: The following 4 themes emerged: preference for humanistic communication, need to account for the role of family in decision making, need for medical information sharing, and mistrust of clinicians. CONCLUSION: Given the dearth of research on SDM among ethnic and racial minorities, this study offers patient-perspective recommendations to improve SDM offerings for Black patients in primary care settings. To enhance SDM with Black patients, acknowledgment of the importance of storytelling as a strategy, to place medical information in a context that makes it meaningful and memorable, is recommended. Triadic SDM, in which family members are centrally involved in decision making, is preferred over classical dyadic SDM. There is a need to reconsider the universalism assumption underlying contemporary SDM models and the relevancy of current SDM practices that were developed mostly without the feedback of participants of ethnic, racial, and cultural minorities.Annals "Online First" article.

Characterization of the Morphological and Chemical Profile of Different Families of Microplastics in Samples of Breathable Air.

Microplastic (MP) contamination has become a problem of great interest to the community at large. The detection of these particles in different ecosystems and foods has been the subject of study. However, the focus of these investigations has been on the identification and quantification of PM by DSC and Pyr-GC/MS and not on how they are transported to reach the air we breathe. In this study, the values of morphological parameters for plastic particles in a range between 1 and 2000 µm, present in the breathable air of 20 neighborhoods in the city of Cartagena, Colombia, were obtained to determine the characteristics that make these particles airborne. The values of parameters were obtained, such as roundness, sphericity, curvature, and the convexity of the particle, as well as its compactness and size, which influence its transport through the air and its ability to be ingested and inhaled. The data obtained in this study allows for simulations and the analysis of the behavior of microplastics once in the environment to predict future settlements. The DSC showed us the melting temperatures of PP, PE, PET, and PS, the Pyr-GC/MS showed the fragmentation patterns, and the presence of these MPs in the samples was confirmed.

Iron Oxide Powder as Responsible for the Generation of Industrial Polypropylene Waste and as a Co-Catalyst for the Pyrolysis of Non-Additive Resins.

For the synthesis of polymeric resins, it is of great importance to review the raw materials and the equipment to be used to avoid the presence of compounds that may affect the effectiveness of the polymerization and the characteristics of the plastic to be obtained. Iron oxide is a compound that can be present in reactors after maintenance due to the techniques used and the cleaning of this equipment, and it can affect the characteristics of the resins, reducing their quality. In this study, the presence of FeO in different concentrations was evaluated to determine its effects on the properties and pyrolysis of polypropylene resins by using X-ray refraction to determine the elements of the samples, evaluating thermal degradation by TGA, the variation in molecular weight by measuring the MFI, and the compounds obtained from pyrolysis by chromatography. The results showed that the thermal degradation decreased as the FeO concentration increased, while for the MFI, the relationship was directly proportional. The evaluation of the compounds obtained from pyrolysis showed an increase in the production of alcohols, alkynes, ketones, and acids, and a decrease in alkanes and alkenes, showing that FeO affects the properties of polypropylene and the compounds that are produced during pyrolysis.

Treatment decision-making needs among emerging adults with early psychosis.

AIM: Many emerging adults disengage from early intervention in psychosis (EIP) services prematurely. Service disengagement may be in part due to having unresolved treatment decision-making needs about use of mental health services. A basic understanding of the decision-making needs of this population is lacking. The purpose of this qualitative study was to identify the range of treatment decisions that emerging adults face during their initial engagement in an EIP program and elucidate barriers and facilitators to decision-making. METHODS: Twenty emerging adults with early psychosis were administered semistructured interviews to capture treatment decision-making experiences during the first six months after enrolment in an EIP program. Interviews were audio-recorded and transcribed verbatim. Responses were independently coded by two authors using an integrated thematic analysis approach; differences in coding were discussed to consensus. Data analysis was facilitated using NVivo 12 Plus. RESULTS: Emerging adults identified numerous decisions faced after EIP enrolment. Decisions pertaining to life and treatment goals and to starting and continuing psychiatric medication were commonly selected as the most difficult/complicated. Decision-making barriers included not having the right amount or type of information/knowledge, social factors (e.g., lacking social support, opposition/pressure), lacking internal resources (e.g., cognitive and communication skills, self-efficacy, motivation) and unappealing options. Obtaining information/knowledge, social supports (e.g., connection/trust, learning from others' experiences, encouragement), considering personal values, and time were decision-making facilitators. CONCLUSIONS: This study informs development and optimization of interventions to support decision-making among emerging adults with early psychosis, which may promote service engagement.

Facilitating treatment engagement for early psychosis through peer-delivered decision support: intervention development and protocol for pilot evaluation.

BACKGROUND: Emerging adults with early psychosis demonstrate high rates of service disengagement from critical early intervention services. Decision support interventions and peer support have both been shown to enhance service engagement but are understudied in this population. The purposes of this article are to describe the development of a novel peer-delivered decision coaching intervention for this population and to report plans for a pilot study designed to gather preliminary data about its feasibility, acceptability, and potential impact. METHODS: The intervention was developed based on formative qualitative data and in collaboration with a diverse team of researchers, key stakeholders, and expert consultants. The pilot trial will utilize a single-group (N = 20), pre-post, convergent mixed-methods design to explore whether and how the intervention addresses decision-making needs (the primary intervention target). The impact of the intervention on secondary outcomes (e.g., engagement in the program) will also be assessed. Additionally, through observation and feedback from the peer decision coach and study participants, we will evaluate the feasibility of research and intervention procedures, and the acceptability of information and support from the peer decision coach. DISCUSSION: The peer-delivered decision coaching intervention holds promise for assisting young people with making informed and values-consistent decisions about their care, and potentially enhancing service engagement within this traditionally difficult-to-engage population. If the intervention demonstrates feasibility and acceptability, and pilot data show its potential for improving treatment decision-making, our work will also lay the foundation for a new evidence base regarding roles for peer specialists on early intervention teams. TRIAL REGISTRATION: This trial was registered with ClinicalTrials.gov (Identifier: NCT04532034 ) on 28 August 2020 as Temple University Protocol Record 261047, Facilitating Engagement in Evidence-Based Treatment for Early Psychosis.

API Content and Blend Uniformity Using Quantum Cascade Laser Spectroscopy Coupled with Multivariate Analysis.

The process analytical technology (PAT) initiative proposed by the US Food and Drug Administration (FDA) suggests innovative methods to better understand pharmaceutical processes. The development of analytical methods that quantify active pharmaceutical ingredients (APIs) in powders and tablets is fundamental to monitoring and controlling a drug product's quality. Analytical methods based on vibrational spectroscopy do not require sample preparation and can be implemented during in-line manufacturing to maintain quality at each stage of operations. In this study, a mid-infrared (MIR) quantum cascade laser (QCL) spectroscopy-based protocol was performed to quantify ibuprofen in formulations of powder blends and tablets. Fourteen blends were prepared with varying concentrations from 0.0% to 21.0% (w/w) API. MIR laser spectra were collected in the spectral range of 990 to 1600 cm-1. Partial least squares (PLS) models were developed to correlate the intensities of vibrational signals with API concentrations in powder blends and tablets. PLS models were evaluated based on the following figures of merit: correlation coefficient (R2), root mean square error of calibration, root mean square error of prediction, root mean square error of cross-validation, and relative standard error of prediction. QCL assisted by multivariate analysis was demonstrated to be accurate and robust for analysis of the content and blend uniformity of pharmaceutical compounds.

Genome Sequences of Three Colombian Helicobacter pylori Strains Isolated from Tolimense Patients.

We present the complete genome sequences of three Helicobacter pylori strains isolated from patients who resided in Tolima Department, Colombia, diagnosed with chronic gastritis. The genomes present an average length of 1.6 Mbp and 1,546 genes and correspond to different H. pylori subpopulations.

Cáncer de mama en seis familias del Tolima y el Huila: mutación BRCA1 3450del4 / Breast cancer in six families from Tolima and Huila: BRCA1 3450del4 mutation

Introducción. El cáncer de mama es un problema mundial de salud pública; entre el 5 y el 10 % de los casos presentan agregación familiar, lo que se explicaría por la presencia de mutaciones en genes de alto riesgo como el BRCA1 y el BRCA2. El origen fundador de la deleción BRCA1 3450del4 en Colombia ya fue reportado. Objetivo. Hacer un análisis descriptivo de seis familias del del Tolima y del Huila con la deleción BRCA1 3450del4 de la asociación de la mutación germinal, con el cáncer de mama y la agregación familiar. Materiales y métodos. Se hizo un estudio descriptivo y transversal de seis casos índice con cáncer de mama positivos para BRCA1 3450del4, que cumplían tres de los criterios establecidos por Jalkh, et al. A partir de la información de las entrevistas, se realizaron los árboles genealógicos (GenoPro™, versión 2016). Se tipificó la mutación en familiares sanos y afectados que aceptaron participar. Resultados. De los 78 individuos seleccionados por conveniencia en las seis familias, 30 presentaron la mutación BRCA1 3450del4; de ellos, seis tenían cáncer de mama, uno, cáncer de ovario, uno, cáncer de mama y ovario, y otro, cáncer de próstata; 21 no presentaban neoplasias. De los 30 individuos portadores de la variante patogénica, seis eran hombres y 24 mujeres, 13 de ellas menores de 30 años. Conclusiones. En este estudio se confirmó la asociación de la deleción BRCA1 3450del4 con el cáncer de mama de agregación familiar.

Introduction: Breast cancer is a worldwide public health problem; between 5% and 10% of the cases present familial aggregation explained by genes of high risk such as BRCA1and BRCA2. The founding origin of the deletion BRCA1 3450del4 in Colombia has been previously reported. Objective: To carry out in six families from Tolima and Huila departments a descriptive analysis of the presence of the BRCA1 3450del4 mutation associated with breast cancer and familial aggregation. Materials and methods: We conducted a descriptive and cross-sectional study of six index cases with breast cancer positive for BRCA1 3450del4 that fulfilled three of the criteria established by Jalkh, et al. The genealogical trees were made using the information of the interview data (GenoPro™, version 2016). The mutation was typified in healthy and affected relatives who agreed to participate. Results: Thirty of the 78 individuals selected by convenience in the six families presented the mutation BRCA1 3450del4 six of whom developed breast cancer, one, ovarian cancer, one ovarian and breast cancer, and one prostate cancer; 21 did not present any type of neoplasm at the time of the study. Of the 30 individuals carrying the pathogenic variant, six were men, 24 were women, and 13 of these were under 30. Conclusions: In this study of families with the deletion BRCA1 3450del4 in Tolima and Huila we confirmed its association with familial aggregation of breast cancer.

An Examination of the Community Participation Interests of Young Adults with Serious Mental Illnesses.

Participation in various aspects of community life (e.g., education, employment) plays a critical role in fostering young adult development and health. To support behavioral health services in addressing a broader array of meaningful community participation areas, the current study examined the participation interests of young adults with serious mental illnesses via a literature review and focus groups interviews. Literature review results revealed a range of community participation areas of interest to these individuals, including employment, education, religion and spirituality, social networking (e.g., using social media), volunteering activities, socializing, and civic and artistic participation (e.g., attending a political event, playing music). Focus group participants named many of these same areas, but also mentioned unique areas of participation that have not been the focus of previous research (i.e., playing games, sports, exploration of other communities (e.g., traveling), hanging out, and nature-based participation). Implications for future research and behavioral health practice are discussed.

Germline Mutations in PALB2, BRCA1, and RAD51C, Which Regulate DNA Recombination Repair, in Patients With Gastric Cancer.

Up to 10% of cases of gastric cancer are familial, but so far, only mutations in CDH1 have been associated with gastric cancer risk. To identify genetic variants that affect risk for gastric cancer, we collected blood samples from 28 patients with hereditary diffuse gastric cancer (HDGC) not associated with mutations in CDH1 and performed whole-exome sequence analysis. We then analyzed sequences of candidate genes in 333 independent HDGC and non-HDGC cases. We identified 11 cases with mutations in PALB2, BRCA1, or RAD51C genes, which regulate homologous DNA recombination. We found these mutations in 2 of 31 patients with HDGC (6.5%) and 9 of 331 patients with sporadic gastric cancer (2.8%). Most of these mutations had been previously associated with other types of tumors and partially co-segregated with gastric cancer in our study. Tumors that developed in patients with these mutations had a mutation signature associated with somatic homologous recombination deficiency. Our findings indicate that defects in homologous recombination increase risk for gastric cancer.

Detection of highly energetic materials on non-reflective substrates using quantum cascade laser spectroscopy.

A quantum cascade laser spectrometer was used to obtain the reflection spectra of highly energetic materials (HEMs) deposited on nonideal, low-reflectivity substrates, such as travel-bag fabric (polyester), cardboard, and wood. Various deposition methods were used to prepare the standards and samples in the study. The HEMs used were the nitroaromatic explosive 2,4,6-trinitrotoluene (TNT), the aliphatic nitrate ester pentaerythritol tetranitrate (PETN), and the aliphatic nitramine 1,3,5-trinitroperhydro-1,3,5-triazine (RDX). Chemometrics algorithms were applied to analyze the recorded spectra. Partial least squares (PLS) regression analysis was used to find the best correlation between the infrared signals and the surface concentrations of the samples, and PLS combined with discriminant analysis (PLS-DA) was used to discriminate, classify, and identity similarities in the spectral datasets. Several preprocessing steps were applied to prepare the mid-infrared spectra of HEMs deposited on the target substrates. The results demonstrate that the infrared vibrational method described in this study is well suited for the rapid screening analysis of HEMs on low-reflectivity substrates when a supervised model has been previously constructed or when a reference spectrum of the clean substrate can be acquired to be subtracted from the HEM-substrate spectrum.

FT-IR standoff detection of thermally excited emissions of trinitrotoluene (TNT) deposited on aluminum substrates.

A standoff detection system was assembled by coupling a reflecting telescope to a Fourier transform infrared spectrometer equipped with a cryo-cooled mercury cadmium telluride detector and used for detection of solid-phase samples deposited on substrates. Samples of highly energetic materials were deposited on aluminum substrates and detected at several collector-target distances by performing passive-mode, remote, infrared detection measurements on the heated analytes. Aluminum plates were used as support material, and 2,4,6-Trinitrotoluene (TNT) was used as the target. For standoff detection experiments, the samples were placed at different distances (4 to 55 m). Several target surface temperatures were investigated. Partial least squares regression analysis was applied to the analysis of the intensities of the spectra obtained. Overall, standoff detection in passive mode was useful for quantifying TNT deposited on the aluminum plates with high confidence up to target-collector distances of 55 m.

[Factors associated with fatal trauma in Medellín (Colombia) motorcyclists]. / Factores asociados al trauma fatal en motociclistas en Medellín, 2005-2008.

INTRODUCTION: Motorcycles have come into widespread use as mode of transport and commuting to work. Given the degree of trauma occurring in motorcycle accidents, this increased use has generated adverse consequences for public health. Categorization of factors associated with these events can form the basis for prevention strategies. OBJECTIVE: The characteristics of person, time, place, vehicle and circumstances of occurrence were described for motorcycle accidents involving rider injury, and the associations were explored with fatal trauma in the city of Medellín, Colombia, in 2005-2008. MATERIALS AND METHODS: A cross-sectional case-control retrospective study was conducted based on population data from the Secretaría de Transporte y Tránsito and Secretaría de Salud. Records were analyzed of incidents involving 24,062 injuries and 345 fatalities. The odds ratio statistic (95% CI) was used to detect significant associations between fatalies and characteristics of trauma exposure; adjusted ORs (95% CI) were obtained by logistic regression analysis. RESULTS: A strong association emerged between fatal trauma and collision with a fixed object. There is a greater chance of dying at railroad crossings, approaches to intersections or roundabouts, and (in the districts of Robledo, Aranjuez and Guayabal) two lane roads. Males, motorcyclists between 20-30 yrs, between 40 and 49 yrs, and >50 yrs were more likely to die. Motorcycle models prior to 1991, travel in early morning hours, or periods of high vehicular density were additional factors of high association. CONCLUSIONS: Because motorcyclists have greater exposure, crashes against fixed objects were much more lethal than in other kinds of events. Although an increased mortality occurred at roundabouts and intersections, a greater mortalities occurred at railroad crossings in the sections of single-rail, double-rail and other configurations.