Glucosylceramides impact cellulose deposition and cellulose synthase complex motility in Arabidopsis.

Cellulose is an abundant component of plant cell wall matrices, and this para-crystalline polysaccharide is synthesized at the plasma membrane by motile Cellulose Synthase Complexes (CSCs). However, the factors that control CSC activity and motility are not fully resolved. In a targeted chemical screen, we identified the alkylated nojirimycin analog N-Dodecyl Deoxynojirimycin (ND-DNJ) as a small molecule that severely impacts Arabidopsis seedling growth. Previous work suggests that ND-DNJ-related compounds inhibit the biosynthesis of glucosylceramides (GlcCers), a class of glycosphingolipid associated with plant membranes. Our work uncovered major changes in the sphingolipidome of plants treated with ND-DNJ, including reductions in GlcCer abundance and altered acyl chain length distributions. Crystalline cellulose content was also reduced in ND-DNJ-treated plants as well as plants treated with the known GlcCer biosynthesis inhibitor N-[2-hydroxy-1-(4-morpholinylmethyl)-2-phenyl ethyl]-decanamide (PDMP) or plants containing a genetic disruption in GLUCOSYLCERAMIDE SYNTHASE (GCS), the enzyme responsible for sphingolipid glucosylation that results in GlcCer synthesis. Live-cell imaging revealed that CSC speed distributions were reduced upon treatment with ND-DNJ or PDMP, further suggesting an important relationship between glycosylated sphingolipid composition and CSC motility across the plasma membrane. These results indicate that multiple interventions compromising GlcCer biosynthesis disrupt cellulose deposition and CSC motility, suggesting that GlcCers regulate cellulose biosynthesis in plants.

Pros and cons of innovations in medical education.

Medical education has implemented various innovative strategies with the purpose to attain better learning achievements. An evaluation is made of the experiences in the competencies approach, new learning technologies, curricular alternatives, professional evaluation and distance education technologies in order to locate them in the areas they belong.

La educación médica ha puesto en práctica diversas estrategias innovadoras con el propósito de alcanzar mejores logros de aprendizaje. Se hace una evaluación de las experiencias relacionadas con el enfoque por competencias, las nuevas tecnologías educativas, las alternativas curriculares, la profesionalización de la evaluación y las técnicas educativas a distancia, para ubicarlas en el lugar que les corresponde.

BRASSINOSTEROID INSENSITIVE2 negatively regulates cellulose synthesis in Arabidopsis by phosphorylating cellulose synthase 1.

The deposition of cellulose is a defining aspect of plant growth and development, but regulation of this process is poorly understood. Here, we demonstrate that the protein kinase BRASSINOSTEROID INSENSITIVE2 (BIN2), a key negative regulator of brassinosteroid (BR) signaling, can phosphorylate Arabidopsis cellulose synthase A1 (CESA1), a subunit of the primary cell wall cellulose synthase complex, and thereby negatively regulate cellulose biosynthesis. Accordingly, point mutations of the BIN2-mediated CESA1 phosphorylation site abolished BIN2-dependent regulation of cellulose synthase activity. Hence, we have uncovered a mechanism for how BR signaling can modulate cellulose synthesis in plants.

Cognitive deterioration in schizophrenia: aging and cerebrovascular disease.

Today, cognitive dysfunction is accepted as a feature of schizophrenia. As the patients age, this dysfunction is higher and harder to evaluate due to the interaction among aging, other somatic diseases, psychoactive drugs, etc.

[Impact of different front-of-pack nutrition labels on foods according to their nutritional quality: a comparative study in Mexico]. / Impacto de diferentes etiquetados frontales de alimentos según su calidad nutricional: estudio comparativo en México.

OBJECTIVE: This study aimed to compare consumers' objec- tive understanding of five FoPLs [Health Star Rating system (HSR), Multiple Traffic Lights (MTL), Nutri-Score, Reference Intakes (RIs), Warning Symbol] in Mexico. MATERIALS AND METHODS: 1 001 Mexican consumers were recruited and asked to rank three sets of label-free products according to their nutritional quality, via a survey. Upon completion of this task, participants were randomized to one of five FoPL condi- tions and were again asked to rank the same sets of products, this time with a FoPL displayed on pack. Change in ability to correctly rank products across the two tasks was assessed by FoPL using ordinal logistic regression. RESULTS: Nutri-Score and MTL performed best, followed Warning Symbol, HSR and RIs. CONCLUSIONS: Nutri-Score and MTL appear as efficient schemes to inform consumers on the nutritional quality of foods, in particular in Mexico, where it would be a helpful tool for consumers in purchasing situations.

OBJETIVO: Evaluar la comprensión objetiva de cinco tipos de etiquetados frontales de paquetes (EFP) (Sistema de Clasifi- cación de Estrellas de Salud, Semáforo Múltiple, Nutri-Score, Ingestas de Referencia y Símbolo de Advertencia) en México. MATERIAL Y MÉTODOS: Se reclutaron 1 001 consumidores mexicanos para clasificar tres productos de tres categorías de alimentos sin EFP, según su calidad nutricional. Se les asignó al azar uno de los cinco EFP para clasificar los mismos productos, esta vez con un EFP en el empaque. El cambio en la capacidad para clasificar correctamente los productos en las dos tareas fue evaluado por EFP, utilizando un modelo de regresión logística ordinal. RESULTADOS: Nutri-Score y Semáforo Múltiple obtuvieron un mejor desempeño, seguidos del Símbolo de Advertencia, Sistema de Clasificación de Estrellas de Salud e Ingestas de Referencia. CONCLUSIONES: Nutri-Score y el Semáforo Múltiple surgen como esquemas eficientes para informar a los consumidores sobre la calidad nutricional de los alimentos en México, donde podrían ser una herramienta útil para los consumidores en situación de compra.

[Performance of medical schools in Mexico: results from the Examen Nacional para Aspirantes a Residencias Médicas]. / Desempeño de las escuelas de medicina en México: resultados del Examen Nacional para Aspirantes a Residencias Médicas.

OBJECTIVE: To assess the performance of medical schools (FEM) by analyzing the results of their applicants in the Examen Nacional para Aspirantes a Residencias Médicas (ENARM). MATERIALS AND METHODS: Five performance criteria, two official and three created on purpose, were calculated from the ENARM-2016 and -2017 official databases to assess FEM performance. RESULTS: In 2016 and 2017, applicants registered from 112 and 115 FEM, respectively. Depending on the performance criteria, the FEM in the first place obtained 5 to 20 points more than the one placed second, and 23 to 98 points more than the FEM in the last place. Approximately 25% applicants were classified as "knowledge-deficient," and about 80% of these originated from less than one third of the FEM. CONCLUSIONS: The ENARM results provide information on the performance of the FEM. Approximately one of every four applicants obtained scores lower than the approval threshold of any specialty.

OBJECTIVE: Evaluar el desempeño de las facultades y escuelas de medicina (FEM) utilizando como subrogado los resultados del Examen Nacional para Aspirantes a Residencias Médicas (ENARM). MATERIALS AND METHODS: Se analizaron las bases de datos oficiales del ENARM 2016 y 2017, empleando cinco criterios de desempeño (CD) por cada FEM: dos oficiales y tres creados exprofeso. RESULTS: En 2016 y 2017 se registraron sustentantes de 112 y 115 FEM, respectivamente. Dependiendo del CD, la FEM que quedó clasificada en el primer lugar obtuvo entre 5 y 20 puntos más que la del segundo lugar, y entre 23 y 98 puntos más que la FEM ubicada en el último lugar. Aproximadamente 25% de los sustentantes fueron calificados como "deficientes en conocimientos" y aproximadamente 80% de éstos provenían de menos de un tercio de las FEM. CONCLUSIONS: El ENARM arroja información sobre el desempeño de las FEM. Aproximadamente uno de cada cuatro sustentantes obtuvo puntajes menores al aprobatorio en cualquier especialidad.

Flaws in the design of the Examen Nacional para Aspirantes a Residencias Médicas produce inequity.

OBJECTIVE: To assess the assumption of 'equity' of Mexico's resident-selection assessment tool, the Examen Nacional para Aspirantes a Residencias Médicas (ENARM). MATERIALS AND METHODS: Official ENARM-2016 and -2017 databases were analyzed. Differences in the absolute number of correct answers (multivariable linear regression) and the number of applicants reaching their specialty minimum score (SMS) per test day (odds ratio [OR]) were calculated. Applicants affected by test-day inequity were estimated. RESULTS: There were 36 114 applicants in 2016, and 38 380 in 2017. In 2016, day-2 applicants had significantly higher scores and more reached the SMS than on days 1-3-4 (OR 1.55), and 5 (OR 3.8); 3 565 non-passing applicants were affected by inequity (equivalent to 44.64% of those selected). In 2017, day-1 and -2 applicants had significantly higher scores and more reached the SMS than on days 3-4 (OR 1.85), and 5 (OR 4.04); 3,155 non-passing applicants were affected by inequity (37.2% of those selected). CONCLUSIONS: Analysis of official ENARM databases does not support the official attribution of equity, suggesting the test should be redesigned.

OBJETIVO: Evaluar el atributo de "equidad" asignado al Examen Nacional para Aspirantes a Residencias Médicas (ENARM). MATERIAL Y MÉTODOS: Se analizaron las bases de datos oficiales del ENARM 2016 y 2017. Se compararon las diferencias inter-día de respuestas correctas (regresión linear multivariable) y de sustentantes que alcanzaron el puntaje mínimo de su especialidad (PME) (razón de momios [RM]). Se estimó a los afectados por la inequidad. RESULTADOS: Hubo 36 114 sustentantes en 2016 y 38 380 en 2017.Los días 2 (ENARM-2016) y 1-2 (ENARM-2017) registraronpuntajes significativamente más altos, y más sustentantes alcanzaron el PME que en los días 1-3-4 (RM .55) y 5 (RM 3.8) en 2016, y los días 3-4 (RM 1.85) y 5 (RM 4.04) en 2017. Se estimó que cuatro de cada diez sustentantes que aprobaron el ENARM no lo hubieran hecho si el examen fuera equitativo. CONCLUSIONES: Los resultados sugieren que el atributo de equidad del ENARM está en duda.

The 2009 pandemic in Mexico: Experience and lessons regarding national preparedness policies for seasonal and epidemic influenza.

Influenza is a viral respiratory disease capable of causing epidemics that represent a threat for global security. Mexico was the first country to notify the WHO of an outbreak of what later became the first influenza pandemic of the 21st Century, caused by the virus A(H1N1)2009. Before this event Mexico had a national pandemic influenza preparedness plan, which included seasonal influenza vaccination, stockpiles of personal protection equipment and strategic drugs, and risk communication strategies. During the epidemic, the national public health laboratory network and case surveillance systems were strengthened together with surge capacities for intensive care and delivery of antiviral drugs. Risk communication was conducted for people to comply with implemented measures regarding social distancing (workplace and school closures, household quarantine). This report describes the Mexican experience during the 2009 influenza pandemic and the lessons that this experience provides to public health preparedness for future pandemics.

[COMPREHENSIVE GERIATRIC ASSESSMENT SCALES]. / Escalas de valoración geriátrica integral.

The process of comprehensive geriatric assessment is one of the key elements of geriatric care management aimed at the population. it includes evaluating the clinical, functional, mental and social aspects of aging result and/or pathological processes that appear at this stage of the life cycle. For their achievement, as well as other tools, professionals have a large number of validated rating scales specifically designed in the assessment of the different areas or fields. Its use can be very useful, especially for the objectification of evaluation results. The future of research in this area goes through deepening the adequacy of the scales to the characteristics and needs of older people in each care level or place of care.

Sensorless FOC Performance Improved with On-Line Speed and Rotor Resistance Estimator Based on an Artificial Neural Network for an Induction Motor Drive.

Three-phase induction motor drive requires high accuracy in high performance processes in industrial applications. Field oriented control, which is one of the most employed control schemes for induction motors, bases its function on the electrical parameter estimation coming from the motor. These parameters make an electrical machine driver work improperly, since these electrical parameter values change at low speeds, temperature changes, and especially with load and duty changes. The focus of this paper is the real-time and on-line electrical parameters with a CMAC-ADALINE block added in the standard FOC scheme to improve the IM driver performance and endure the driver and the induction motor lifetime. Two kinds of neural network structures are used; one to estimate rotor speed and the other one to estimate rotor resistance of an induction motor.

Surveillance of Oseltamivir-Resistant Influenza A(H1N1)pdm09 in Guanajuato State, Mexico from 2009 to 2012.

BACKGROUND: The influenza A(H1N1)pdm09 virus was first identified in Mexico in April 2009, subsequently spreading worldwide. Soon after the WHO declared a pandemic, a series of cases involving oseltamivir-resistant viruses were described, following concerns about the spread of strains resistant to neuraminidase inhibitors that could hamper control measures. To study the prevalence of oseltamivir-resistant influenza A(H1N1)pdm09, we implemented a surveillance program across the state of Guanajuato, Mexico. METHODS: We collected respiratory samples from patients with confirmed infection with influenza A(H1N1)pdm09 virus between 2009 and 2012 in rural and urban regions in Guanajuato, Mexico. Specimens were screened for the H275Y mutation by Sanger sequencing. RESULTS: A total of 1,192 laboratory confirmed influenza A(H1N1)pdm09-positive samples were processed between 2009 and 2012. Using two endpoint real-time polymerase chain reaction, 575 samples were sequenced. Two different clusters, I and II, were identified. The H275Y substitution was found in only one sample from cluster I. CONCLUSIONS: The prevalence of oseltamivir-resistant influenza A(H1N1)pdm09 2009 viruses during the pandemic period and following years was very low in our State.

Prevalence of Oppositional Defiant Disorder in a sample of Spanish children between six and sixteen years: teacher’s report.

INTRODUCTION: Our main objective is to study the prevalence of Oppositional Defiant Disorder (ODD) in school children aged 6-16 years of an autonomous region of Spain (Castile and Leon), according to reports from the teachers and to analyze the impact of the disorder on academic performance and school behavior. METHODS: Population study with stratified multistage, proportional and cluster design sample. Sample analyzed: 1,049. Cases were defined according to DSM-IV-TR criteria. RESULTS: An overall prevalence rate of 4.2% was found, this being significantly higher in males (5.7%) compared to females (2.6%) and in rural (6.8%) than in urban areas (3%). No significant differences by grade or type of school were found. ODD prevalence without considering functional impairment would increase to 5.1%. ODD cases have significantly worse academic outcomes (overall academic performance, reading, math and writing) and entail worse classroom behavior (relationship with peers, respect for rules, organizational skills, academic tasks and disruption of the class). CONCLUSIONS: Based on the prevalence, early onset, persistence of symptoms and social and academic dysfunction of ODD, early diagnosis and preventive intervention are necessary.

Differential expression of C-reactive protein and serum amyloid A in different cell types in the lung tissue of chronic obstructive pulmonary disease patients.

BACKGROUND: Chronic systemic inflammatory syndrome has been implicated in the pathobiology of extrapulmonary manifestations of chronic obstructive pulmonary disease (COPD). We aimed to investigate which cell types within lung tissue are responsible for expressing major acute-phase reactants in COPD patients and disease-free ("resistant") smokers. METHODS: An observational case-control study was performed to investigate three different cell types in surgical lung samples of COPD patients and resistant smokers via expression of the C-reactive protein (CRP) and serum amyloid A (SAA1, SAA2 and SAA4) genes. Epithelial cells, macrophages and fibroblasts from the lung parenchyma were separated by magnetic microbeads (CD326, CD14 and anti-fibroblast), and gene expression was evaluated by RT-PCR. RESULTS: The sample consisted of 74 subjects, including 40 COPD patients and 34 smokers without disease. All three cell types were capable of synthesizing these biomarkers to some extent. In fibroblasts, gene expression analysis of the studied biomarkers demonstrated increased SAA2 and decreased SAA1 in patients with COPD. In epithelial cells, there was a marked increase in CRP, which was not observed in fibroblasts or macrophages. In macrophages, however, gene expression of these markers was decreased in COPD patients compared to controls. CONCLUSIONS: These results provide novel information regarding the gene expression of CRP and SAA in different cell types in the lung parenchyma. This study revealed differences in the expression of these markers according to cell type and disease status and contributes to the identification of cell types that are responsible for the secretion of these molecules.

A new species of the alpheid shrimp genus Triacanthoneus Anker, 2010 (Crustacea: Alpheidae) from Belize.

A new species of the alpheid shrimp genus Triacanthoneus Anker, 2010, is described based on material collected in a marine cave off Caye Chapel, Belize. Triacanthoneus chapelianus sp. nov. is the fifth species in the genus and can be distinguished from the other four species by the position of the dorsolateral teeth on the carapace, which in the new species have an anterior (= submarginal) position, and by the configuration of the posterior margin of the telson, with a notch in the middle portion and two pairs of spines and one pair of plumose setae. A key to the five species of Triacanthoneus is provided.

Structure and genetic variability of the Costa Rican Paso horse.

The Costa Rican Paso Horse (CPC) is a breed developed in Costa Rica. The objectives were to estimate the genetic structure and evaluate the levels of genetic variability of the population. The genotypes of 14 microsatellites in 3654 records (2052 females and 1602 males) were analyzed. Expected (He) and observed (Ho) heterozygosity, polymorphic information content (CIP), fixation index (FIS), Shannon index, as well as Hardy-Weinberg disequilibrium (DHW) were evaluated. Kinship relationships (Rij) were estimated throughout the entire population. The effective population size (Ne) was calculated, alternating allele frequencies less than 0.05, 0.02 and 0.01. The Bayesian clustering study was carried out to infer how many lines are appropriate from the analysis of genotypes using multiple loci. The number of alleles per locus ranged from 7 to 17, with an average value of 9.6; nine loci presented DHW (P < 0.05); two loci presented negative FIS values, the same as Ho > He; the average of CIP, Ho and He was 0.254, 0.756 and 0.785, respectively. At the 12 loci where He > Ho, the differences ranged from 0.002 to 0.341 (0.036 on average). For Ne, the estimates were 201.9, 230.1, and 241.5. In the Rij, 54.86% of the estimates were in the interval of 0.01 to 77.7%. The number of lines that define the population corresponds to three, with an approximate composition of 33.1%, 32.4% and 34.5%, respectively. The CPC, as a subdivided population with DHW and a reduction in heterozygotes may be associated with possible Wahlund effects. Keywords: Wahlund effect, equines, genetic markers, synthetic breed, Hardy Weinberg.

Computational Analysis of Polymeric Biodegradable and Customizable Airway Stent Designs.

The placement of endotracheal prostheses is a procedure used to treat tracheal lesions when no other surgical options are available. Unfortunately, this technique remains controversial. Both silicon and metallic stents are used with unpredictable success rates, as they have advantages but also disadvantages. Typical side effects include restenosis due to epithelial hyperplasia, obstruction and granuloma formation. Repeat interventions are often required. Biodegradable stents are promising in the field of cardiovascular biomechanics but are not yet approved for use in the respiratory system. The aim of the present study is to summarize important information and to evaluate the role of different geometrical features for the fabrication of a new tracheo-bronchial prosthesis prototype, which should be biodegradable, adaptable to the patient's lesion and producible by 3D printing. A parametric design and subsequent computational analysis using the finite element method is carried out. Two different stent designs are parameterized and analyzed. The biodegradable material chosen for simulations is polylactic acid. Experimental tests are conducted for assessing its mechanical properties. The role of the key design parameters on the radial force of the biodegradable prosthesis is investigated. The computational results allow us to elucidate the role of the pitch angle, the wire thickness and the number of cells or units, among other parameters, on the radial force. This work may be useful for the design of ad hoc airway stents according to the patient and type of lesion.

Two new genera and three new species of freshwater crabs (Crustacea: Pseudothelphusidae: Potamocarcinini) from Chiapas, Mexico.

Two new genera, Sylvathelphusa n. gen. and Tzotzilthelphusa n. gen., and three new species, Sylvathelphusa kalebi n. sp., S. cavernicola n. sp. and Tzotzilthelphusa villarosalensis n. sp., of the tribe Potamocarcinini, family Pseudothelphusidae, are described from Chiapas, Mexico. Sylvathelphusa n. gen. is characterized by a male gonopod with the marginal plate between the caudal and mesial surfaces abruptly widening distally and forming a triangular apical projection; and a mesial process as a strong, acute spine forming a 90º angle with respect to the principal axis of the gonopod. Tzotzilthelphusa n. gen. exhibits a male gonopod strongly bent laterally in the distal third, and a mesial surface rounded distally with acute spinules. Sylvathelphusa n. gen. is similar to Potamocarcinus in gonopod morphology, in both straight and with a mesial process developed as strong tooth in a similar shape and position. Tzotzilthelphusa n. gen. is similar to Phrygiopilus in that the gonopods of both genera develop a supra-apical process that is a continuation of the mesial surface. The new taxa come from the Los Altos de Chiapas region and bring the total number of pseudothelphusid genera in Chiapas to 11.

Insight into ADHD diagnosis with deep learning on Actimetry: Quantitative interpretation of occlusion maps in age and gender subgroups.

Attention Deficit/Hyperactivity Disorder (ADHD) is a prevalent neurodevelopmental disorder in childhood that often persists into adulthood. Objectively diagnosing ADHD can be challenging due to the reliance on subjective questionnaires in clinical assessment. Fortunately, recent advancements in artificial intelligence (AI) have shown promise in providing objective diagnoses through the analysis of medical images or activity recordings. These AI-based techniques have demonstrated accurate ADHD diagnosis; however, the growing complexity of deep learning models has introduced a lack of interpretability. These models often function as black boxes, unable to offer meaningful insights into the data patterns that characterize ADHD. OBJECTIVE: This paper proposes a methodology to interpret the output of an AI-based diagnosis system for combined ADHD in age and gender-stratified populations. METHODS: Our system is based on the analysis of 24 hour-long activity records using Convolutional Neural Networks (CNNs) to classify spectrograms of activity windows. These windows are interpreted using occlusion maps to highlight the time-frequency patterns explaining ADHD activity. RESULTS: Significant differences in the frequency patterns between ADHD and controls both in diurnal and nocturnal activity were found for all the populations. Temporal dispersion also presented differences in the male population. CONCLUSION: The proposed interpretation techniques for CNNs highlighted gender- and age-related differences between ADHD patients and controls. Leveraging these differences could potentially lead to improved diagnostic accuracy, especially if a larger and more balanced dataset is utilized. SIGNIFICANCE: Our findings pave the way for the development of an AI-based diagnosis system for ADHD that offers interpretability, thereby providing valuable insights into the underlying etiology of the disease.

Low-Dose Gamma Radiation Sterilization for Decellularized Tracheal Grafts.

One of the main key aspects in ensuring that a transplant evolves correctly is the sterility of the medium. Decellularized tracheal transplantation involves implanting an organ that was originally in contact with the environment, thus not being sterile from the outset. While the decellularization protocol (through detergent exposition [2% sodium dodecyl sulfate], continuous stirring, and osmotic shocks) is conducted in line with aseptic measures, it does not provide sterilization. Therefore, one of the main challenges is ensuring sterility prior to in vivo implantation. Although there are established gamma radiation sterilization protocols for inorganic materials, there are no such measures for organic materials. Additionally, the protocols in place for inorganic materials cannot be applied to organic materials, as the established radiation dose (25 kGy) would completely destroy the implant. This paper studies the effect of an escalated radiation dose in a decellularized rabbit trachea. We maintained the dose range (kGy) and tested escalated doses until finding the minimal dose at which sterilization is achieved. After determining the dose, we studied effects of it on the organ, both histologically and biomechanically. We determined that while 0.5 kGy did not achieve sterility, doses of both 1 kGy and 2 kGy did, with 1 kGy, therefore, being the minimal dose necessary to achieve sterilization. Microscopic studies showed no relevant changes compared to non-sterilized organs. Axial biomechanical characteristics were not altered at all, and only a slight reduction in the force per unit of length that the organ can radially tolerate was observed. We can therefore conclude that 1 kGy achieves complete sterilization of decellularized rabbit trachea with a minimal, if any, effects on the organ.

Pneumonia and respiratory failure from swine-origin influenza A (H1N1) in Mexico.

BACKGROUND: In late March 2009, an outbreak of a respiratory illness later proved to be caused by novel swine-origin influenza A (H1N1) virus (S-OIV) was identified in Mexico. We describe the clinical and epidemiologic characteristics of persons hospitalized for pneumonia at the national tertiary hospital for respiratory illnesses in Mexico City who had laboratory-confirmed S-OIV infection, also known as swine flu. METHODS: We used retrospective medical chart reviews to collect data on the hospitalized patients. S-OIV infection was confirmed in specimens with the use of a real-time reverse-transcriptase-polymerase-chain-reaction assay. RESULTS: From March 24 through April 24, 2009, a total of 18 cases of pneumonia and confirmed S-OIV infection were identified among 98 patients hospitalized for acute respiratory illness at the National Institute of Respiratory Diseases in Mexico City. More than half of the 18 case patients were between 13 and 47 years of age, and only 8 had preexisting medical conditions. For 16 of the 18 patients, this was the first hospitalization for their illness; the other 2 patients were referred from other hospitals. All patients had fever, cough, dyspnea or respiratory distress, increased serum lactate dehydrogenase levels, and bilateral patchy pneumonia. Other common findings were an increased creatine kinase level (in 62% of patients) and lymphopenia (in 61%). Twelve patients required mechanical ventilation, and seven died. Within 7 days after contact with the initial case patients, a mild or moderate influenza-like illness developed in 22 health care workers; they were treated with oseltamivir, and none were hospitalized. CONCLUSIONS: S-OIV infection can cause severe illness, the acute respiratory distress syndrome, and death in previously healthy persons who are young to middle-aged. None of the secondary infections among health care workers were severe.