Short-Term Effects of Atmospheric Pollution on Daily Mortality and Their Modification by Increased Temperatures Associated with a Climatic Change Scenario in Northern Mexico.

Short-term effects of air pollution on the health of residents in the Metropolitan Area of Monterrey, Mexico were assessed from 2012-2015 using a time-series approach. Guadalupe had the highest mean concentrations for SO2, CO and O3; whereas Santa Catarina showed the highest NO2 concentrations. Escobedo and Garcia registered the highest levels for PM10. Only PM10 and O3 exceeded the maximum permissible values established in the Mexican official standards. Most of pollutants and municipalities showed a great number of associations between an increase of 10% in their current concentrations and mortality, especially for people >60 years. Different scenarios resulting from climatic change were built (increases of 5-25% in daily mean temperature), but only the increase of 25% (5 °C) showed a significant association with air pollutant concentrations and mortality. All pollutants and municipalities showed significant increases in relative risk indexes (RRI) resulting from an increase of 5 °C when people >60 years was considered. Results were comparable to those reported by other authors around the world. The RRI were low but significant, and thus are of public concern. This study demonstrated that the elderly is strongly threatened not only by atmospheric pollution but also by climatic change scenarios in warm and semiarid places.

A Low-Cost Calibration Method for Low-Cost MEMS Accelerometers Based on 3D Printing.

A ubiquitous sensor in embedded systems is the accelerometer, as it enables a range of applications. However, accelerometers experience nonlinearities in their outputs caused by error terms and axes misalignment. These errors are a major concern because, in applications such as navigations systems, they accumulate over time, degrading the position accuracy. Through a calibration procedure, the errors can be modeled and compensated. Many methods have been proposed; however, they require sophisticated equipment available only in laboratories, which makes them complex and expensive. In this article, a simple, practical, and low-cost calibration method is proposed. It uses a 3D printed polyhedron, benefiting from the popularisation and low-cost of 3D printing in the present day. Additionally, each polyhedron could hold as much as 14 sensors, which can be calibrated simultaneously. The method was performed with a low-cost sensor and it significantly reduced the root-mean-square error (RMSE) of the sensor output. The RMSE was compared with the reported in similar proposals, and our method resulted in higher performance. The proposal enables accelerometer calibration at low-cost, and anywhere and anytime, not only by experts in laboratories. Compensating the sensor's inherent errors thus increases the accuracy of its output.

Lightweight Authentication Protocol for M2M Communications of Resource-Constrained Devices in Industrial Internet of Things.

The Industrial Internet of Things (IIoT) consists of sensors, networks, and services to connect and control production systems. Its benefits include supply chain monitoring and machine failure detection. However, it has many vulnerabilities, such as industrial espionage and sabotage. Furthermore, many IIoT devices are resource-constrained, which impedes the use of traditional security services for them. Authentication allows devices to be confident of each other's identity, preventing some security attacks. Many authentication protocols have been proposed for IIoT; however, they have high computing requirements not viable to resource-constrained devices, or they have been found insecure. In this paper, an authentication protocol for resource-constrained IIoT devices is proposed. It is based on the lightweight operations xor, addition, and subtraction, and a hash function. Also, only four messages are exchanged between the principals to authenticate. It has a low execution-time and communication-cost. Its security was successfully assessed with the formal methods Automated Validation of Internet Security Protocols and Applications (AVISPA) tool and Burrows-Abadi-Needham (BAN) logic, together with an informal analysis of its resistance to known attacks. Its performance and security were compared with state-of-the-art protocols, resulting in a good performance for resource-constrained IIoT devices, and higher security similar to computational expensive schemes.

A Lightweight Cipher Based on Salsa20 for Resource-Constrained IoT Devices.

The Internet of Things (IoT) paradigm envisions a world where everyday things interchange information between each other in a way that allows users to make smarter decisions in a given context. Even though IoT has many advantages, its characteristics make it very vulnerable to security attacks. Ciphers are a security primitive that can prevent some of the attacks; however, the constrained computing and energy resources of IoT devices impede them from implementing current ciphers. This article presents the stream cipher Generador de Bits Pseudo Aleatorios (GBPA) based on Salsa20 cipher, which is part of the eSTREAM project, but designed for resource-constrained IoT devices of Class 0. GBPA has lower program and data memory requirements compared with Salsa20 and lightweight ciphers. These properties allow low-cost resource-constrained IoT devices, 29.5% of the embedded systems in the market, to be able to implement a security service that they are currently incapable of, to preserve the user's data privacy and protect the system from attacks that could damage it. For the evaluation of its output, three statistical test suites were used: NIST Statistical Test Suite (STS), DIEHARD and EACirc, with good results. The GBPA cipher provides security without having a negative impact on the computing resources of IoT devices.

[Group B streptococcal perinatal infection: A Global, Latin American and Mexican Overview]. / Infección perinatal por estreptococo del grupo B: panorama global, en América Latina y en México.

Group B streptococci (Streptococcus agalactiae) cause a number of infections in women during pregnancy and postpartum, such as urinary tract infection, chorioamnionitis and endometritis, consequently may affect the newborn. Group B streptococci is the most common cause of severe infections in newborns in developed countries. Studies on the epidemiology of group B streptococci infections in Latin America are still limited. This information is also unknown in Mexico, but studies carried out in the center of the country have found high rates of vaginal colonization in pregnant women and there are case series and case reports of newborns. Microbiological and molecular epidemiology studies in Mexico have shown that populations of group B streptococci have a clonal distribution and that there are clones with genetic and phenotypic characteristics of high virulence that appear to be responsible for most of perinatal pathology. However, the actual role of group B streptococci in perinatal pathology in Mexico is unknown. Consequently, whether to perform or not the screening for determining the group B streptococci colonization status in pregnant women, and the indication or not for intrapartum antibiotic prophylaxis to prevent neonatal group B streptococci infection in Mexico, are still controversial.

[Assessment of antibiotic use and impact of an intervention intended to modify the prescribing behavior in surgical prophylaxis in 6hospitals in the metropolitan area of Monterrey, Mexico]. / Evaluación del uso de antibióticos e impacto de una intervención dirigida a modificar la conducta prescriptiva en profilaxis quirúrgica en 6hospitales del área metropolitana de Monterrey.

BACKGROUND: Improper use of antibiotics increases antimicrobial resistance. OBJECTIVE: Evaluate the use of antibiotics and the impact of an intervention designed to improve antibiotic prescription for surgical prophylaxis in 6 hospitals of Monterrey, Mexico. MATERIAL AND METHODS: Design: A prospective multicenter survey and a pretest-postest experimental study. Phase 1: Survey to evaluate the use of antibiotics through an especially designed guide. Phase 2: Intervention designed to improve antibiotic prescription for surgical prophylaxis by the medical staff by using printed, audiovisual and electronic messages. Phase 3: Survey to evaluate the impact of the intervention. ANALYSIS: Frequencies, percentages, medians, ranges and X2 test. RESULTS: Phase 1: We evaluated 358 surgical patients, 274 prophylactic antibiotic regimens. A total of 96% of antibiotics regimens began with inappropriate timing (290/302), 82.8% were inappropriate regimens (274/331), 77.7% were in inappropriate dosage (230/296), 86% of inadequate length (241/280), and in 17.4% restricted antibiotics were used (52/299). Phase 2: 9 sessions including 189 physicians (14 department chairs, 58 general practitioners and 117 residents). Phase 3: We evaluated 303 surgical patients, 218 prophylactic antibiotics regimens. Inappropriate treatment commencement was reduced to 84.1% (180/214) (P<0.001), inappropriate regimens to 75.3% (162/215) (P=0.03), inappropriate dosages to 51.2% (110/215) (P<0.001), and use of restricted antibiotics to 8.3% (18/215) (P=0.003). CONCLUSIONS: Inappropriate use of prophylactic antibiotics in surgery is a frequent problem in Monterrey. The intervention improved the antibiotic prescription for surgical prophylaxis by reducing inappropriate treatment commencement, regimens, dosages, and overuse of restricted antibiotics. It is necessary to strengthen strategies to improve the prescription of antibiotics in surgical prophylaxis.

Mutations Related to Antiretroviral Resistance Identified by Ultra-Deep Sequencing in HIV-1 Infected Children under Structured Interruptions of HAART.

Although Structured Treatment Interruptions (STI) are currently not considered an alternative strategy for antiretroviral treatment, their true benefits and limitations have not been fully established. Some studies suggest the possibility of improving the quality of life of patients with this strategy; however, the information that has been obtained corresponds mostly to studies conducted in adults, with a lack of knowledge about its impact on children. Furthermore, mutations associated with antiretroviral resistance could be selected due to sub-therapeutic levels of HAART at each interruption period. Genotyping methods to determine the resistance profiles of the infecting viruses have become increasingly important for the management of patients under STI, thus low-abundance antiretroviral drug-resistant mutations (DRM's) at levels under limit of detection of conventional genotyping (<20% of quasispecies) could increase the risk of virologic failure. In this work, we analyzed the protease and reverse transcriptase regions of the pol gene by ultra-deep sequencing in pediatric patients under STI with the aim of determining the presence of high- and low-abundance DRM's in the viral rebounds generated by the STI. High-abundance mutations in protease and high- and low-abundance mutations in reverse transcriptase were detected but no one of these are directly associated with resistance to antiretroviral drugs. The results could suggest that the evaluated STI program is virologically safe, but strict and carefully planned studies, with greater numbers of patients and interruption/restart cycles, are still needed to evaluate the selection of DRM's during STI.

[Comparison of the tests polymerase chain reaction, serology, and blood culture with respect to sensitivity and specificity for detection of Brucella spp in human samples]. / Comparación de las pruebas: reacción en cadena de la polimerasa (PCR), serología y hemocultivo con respecto a sensibilidad y especificidad, para la detección de Brucella spp en muestras humanas.

OBJECTIVE: The aim of this study was to evaluate the sensitivity and specificity of polymerase chain reaction for detection of Brucella spp in human blood samples compared with the serological tests and blood culture. MATERIAL AND METHODS: In 2005, a total of 92 people were sampled from the towns of Anahuac and Sabinas Hidalgo, Nuevo Leon, where an outbreak of human cases had taken place in the same year as this study. The sera collected were analyzed by serological tests according to the NOM 022-SS2-1994. DNA was obtained using CTAB extraction method and it was used to amplify a fragment of 223 bp of the coding sequence for a protein of 31 kDa present in all Brucella species. RESULTS: The polymerase chain reaction test detected 23 positive samples. The sensitivity and specificity compared with RB was 44.68 and 95.56%, respectively. Compared with mouse antibody production, it was 51.61 and 88.52%, and 2-mercaptoethanol was 53.57 and 87.50%. When isolation (positives cultures) was compared with polymerase chain reaction, we obtained 100.0% sensitivity and 80.23% specificity, taking into account people with positive and negative serology. CONCLUSIONS: The polymerase chain reaction test can be an alternative tool to bacterial culture in human brucellosis diagnosis.

[Prolonged exposure to antibiotics and the risk of late-onset sepsis (LOS) in neonates of 1,000-1,500 g: a cohort study]. / Exposición prolongada a antibióticos y riesgo de sepsis tardía (ST) en neonatos de 1,000 a <1,500 g: estudio de cohorte.

OBJECTIVE: To determine whether prolonged exposure to antibiotics (>5 days) increases the risk of late-onset sepsis (LOS) in newborns of 1,000-1,500 g. METHODS: A cohort study in newborns with suspected perinatal infection, with a survival greater than seven days. The exposed cohort was composed of newborns with antibiotic therapy initiated at first postnatal day, lasting >5 days, with negative blood cultures before the fifth day of life, and without clinical evidence of sepsis. The non-exposed cohort was identical but with antibiotics stopped before the fifth day of life. Patients were followed daily for clinical and laboratory evidence of LOS. Others risk factors for LOS were analyzed. STATISTICAL ANALYSIS: We analyzed the incidence, the relative risk (RR) with 95% CI. To measure the time to occurrence of an event of LOS after exposure, Kaplan-Meier survival curve and log-rank test were used. RESULTS: We followed up 49 patients in each group. The incidence was 33.6%. The time of follow-up was 839 vs. 1,291 person-days. Prolonged exposure to antibiotics was associated with a higher risk of LOS (RR: 21.1; 95% CI: 6.5-68.9; p=0.000). The late-onset sepsis-free time was 17.1±1.1 vs. 26.3±0.8 days. CONCLUSIONS: The risk of LOS was higher in newborns with prolonged exposure to antibiotics and increased with the days of exposure.

An analysis of unused and expired medications in Mexican households.

BACKGROUND: Unsafe storage of unused medications at home leads to an increased risk of toxicity, accidental childhood poisoning or risk for suicide, whereas an improper disposal of unwanted/expired medications from household raises concern about environmental pollution. OBJECTIVE: The aim of the study was to characterize expired medications collected according to the types of therapeutic groups, pharmaceutical dosage forms, expiration dates and were prescribed or over the counter drugs, and whether they came from Mexican health system or purchased by patients themselves. SETTING: The study was conducted in the metropolitan area of Monterrey during a 12-month period from March 2012 to February 2013. METHOD: Unused/expired drugs were collected according to the collection and disposal of expired medication program instituted by the Department of Health of the State of Nuevo León. Pharmacists and students from The Autonomous University of Nuevo León recorded types of therapeutic groups, total of medicines in each group, among other classification criteria. MAIN OUTCOME MEASURE: The proportion of every collected therapeutic group, type of dosage forms, and expiration date. RESULTS: The amount of medications classified was 22,140 items corresponding to a 30 % of the total collected medications in that period of time; most of them belonged to the non-steroidal anti-inflammatory drugs (16.11 %). According to the pharmaceutical dosage forms, results showed that a high percentage were solid dosage forms (73.39 %), of the total unused/expired medications, most of them were prescription drugs (91 %) which were purchased at private pharmacies. Expiration date of medications ranges from 1995 to 2016, being 2011 the outstanding year (36.66 %). CONCLUSION: Addressing the aspect of unused drug disposition constitutes a challenge for Mexican government, due to health implications related to inadequate disposition. No matter how efficient the programs of collection and disposal of expired drugs are, none of them can collect all unused or expired drugs, that is the reason why the best approach might be to prevent this need.

Temporal analysis of PM10 in Metropolitan Monterrey, México.

The Monterrey Metropolitan Area (MMA) is the third largest city in Mexico. Few studies have been carried out regarding its air pollution. The aim of this study was to analyze the temporal behavior of PM10 (particulate matter < or =10 microm in aerodynamic diameter). Data reported by the "Sistema Integral de Monitoreo Ambiental" (Integrated Environmental Monitoring System) network from 2006 to 2008 were used. PM10 levels were compared among the stations by year, season, and day of week. A bootstrap technique was used to obtain subsamples to which Student's t test and ANOVA were applied. PM10 levels were high and exceeded the annual limit of 50 microg/m3 set up by the Mexican standard Norma Oficial Mexicana NOM-025-SSA1-1993. These levels could have serious health effects. The southwest zone of MMA had the highest levels of PM10 during the period studied. Winter was the most polluted season, and summer was the least polluted season. Thursday and Friday were the most polluted days, and Sunday was the least polluted day. The hours with the highest levels of PM10 were 8:00 to 10:00 a.m., whereas nighttime hours were the cleanest.

[Response to the treatment of brucellosis among children. Evaluation with Huddleson reaction and PCR]. / Respuesta al tratamiento de brucelosis en niños. Evaluación con reqcción de Huddleson y PCR.

INTRODUCTION: Brucellosis poses a significant public health problem and requires meticulous diagnosis; the outcome has frequent relapses even when the treatment is appropriate. OBJECTIVE: To evaluate the response to the treatment in children with brucellosis by means of Huddleson seroaglutination test and PCR. METHODS: Using a prospective design, a cohort of children with brucellosis was followed up by carrying out Huddleson seroaglutination test of and PCR for Brucella at 6, 12 and 24 weeks. Most of children were treated with trimetoprim + sulfametoxazole and rifampicine. The progress towards therapeutic failure or relapse was evaluated. RESULTS: Twenty-three children fulfilled the inclusion criteria. The median age was 4.7 years; 61 % had consumed potentially infected milk or dairy products. The duration of symptoms ranged from 7 days to 1 year. Brucella sp. was isolated in blood culture in two of 21 children and Brucella melitensis in myeloculture in one of four children. 69 % had positive Huddleson serological test from 1:160 to >1:12000. PCR tested positive in 100% of children when entering to the study. Six weeks after beginning treatment 17% of children had therapeutic failure. At 12 weeks, three children (13 %) persisted with positive PCR and their antimicrobial treatment was modified. At 24 weeks, five children (21.7 %) presented relapse. A child persisted positive in spite of modifying the antimicrobial scheme. The agreement between the two tests was low in the three follow-up periods (k = 0.08, k = 0.12 and k = 0.28 respectively). CONCLUSIONS: A 6-week treatment cannot be enough to eliminate Brucella. PCR test can be used to early identify relapses.

[Microalbuminuria in patients with type 2 diabetes]. / Microalbuminuria en pacientes con diabetes tipo 2.

OBJECTIVE: To identify microalbuminuria in patients with type 2 diabetes. MATERIAL AND METHODS: A descriptive cross-section study was made in patients with type 2 diabetes with more than a year of evolution. Microalbuminuria was defined as the presence of 30 to 300 mg of albumin in urine of 24 hours. The socio-demographic characteristics, type of diet, exercise, type of antihypertensive and oral antihyperglycemic agents were analyzed. Basal glycemia after one and two months, and renal state were assessed. RESULTS: Of 301 type 2 diabetic patients, 251 had microalbuminuria. The mean age was 57.2 years old. Women predominated over men (1.4:1). The mean for diabetes evolution was nine years. The complication with more frequency was hypertensive cardiopathy 78.1 %. A medium protein diet was present in 49%. 62.2% exercised and 40.2% exercised less than 30 minutes. Mean GFR with creatinine clearance was 83.3 +/- 32 mL/min. 98% of the cases received oral antihyperglycemic agents. Basal glycemia, after one and two months, was, on average, 171.8 mg/dL, 190.1 mg/dL, and 217.4 mg/dL. 74.5% of the patients had hyperglycemia in the first measuring, 79.3% in the second one, and 70.5% in the third one. CONCLUSIONS: The prevalence of microalbuminuria was greater than the reported in literature (85.3%). A poor control of glycemia was showed.

Manejo profiláctico con antibióticos en neurocirugía (cefataxima vs. cefuroxima) / Prophylactic management using antimicrobial drugs in neurosurgery (cefotaxime vs. cefuroxime)

Objetivo: Determinar la eficacia de dos antibióticos (cefotaxima vs. cefuroxima) en la profilaxis de infecciones posquirúrgicas en cirugías limpias y limpias contaminadas en pacientes neuroquirúrgicos. Material y métodos: En el servicio de neurocirugía se realizaron 136 intervenciones quirúrgicas entre los meses de octubre a noviembre de 1994. Los criterios de inclusión fueron: ausencia de infección en otro órgano, cirugía limpia o limpia contamida, sin colocación de material sintético (DVP o craneoplastic). Los pacientes se dividieron en dos grupos: a los del grupo A se les dio cefotaxima y a los del B cefuroxima. Los antibióticos se prescribieron durante un periodo no mayor de 24 horas. La primera dosis de aplicó en el transcurso de la hora previa al inicio de la operación y cada cuatro horas durante la misma. La última dosis se administró cuatro horas después de terminada la intervención. La cefotaxima se aplicó a la dosis de un gramo cada vez y la cefuroxima a 750 mg por dosis. En los pacientes pediátricos la dosis se ajustó a 30 mg/kg de peso en ambos grupos. Resultados: Se incluyeron 54 pacientes, 28 del sexo masculino y 26 del femenino. El rango de edad fue de 3 a 75 años. Cada grupo estuvo conformado por 27 pacientes. Los procedimientos quirúrgicos fueron 33 craneotomías, nueve craniectomías suboccipitales, cinco transesfenoidales y siete espinales. El tiempo quirúrgico varió de 2 a 8 horas. El tiempo de utilización del microscopio fue, en promedio, de dos horas. Sólo hubo un caso de infección superficial en el grupo de la cefuroxima. No hubo diferencia estadísticamente significaiva entre los dos antibióticos utilizados (p exacta de Fisher = 0.5). conclusión: la incidencia de infecciones posquirúrgicas (limpias contaminadas) en neurocirugía es baja (3.7 por ciento). La profilaxis antibiótica puede usarse durante un tiempo menor de 24 horas. No hubo diferencia en la eficacia de los antibióticos utilizados, por lo que consideramos que es posible utilizar un antibiótico de menor costo y de mejor espectro contra gérmenes grampositivos (Staphylococcus aureus), como la cefuroxima, en el profilaxis de pacientes neuroquirúrgicos

Eficacia y seguridad de la profilaxis en cirugía cardiovascular con tres esquemas terapéuticos / Efficacy and security of cardiovascular surgery prophylaxis with three therapeutic schemes

Introducción. La profilaxis con antibióticos en cirugía cardiovascular disminuye la frecuencia de infecciones postoperatorias. Objetivo. Evaluar la eficacia y seguridad de tres esquemas de antibióticos empleados en nuestro hospital en cirugía cardiaca. Pacientes y métodos. Se realizó un estudio prospectivo, longitudinal, aleatorio y parcialmente controlado en 89 pacientes adultos sometidos a cirugía cardiovascular, entre marzo y agosto de 1995. Los pacientes se dividieron en tres grupos según el tratamiento recibido: A-cefuroxima (28 pacientes), B-cefalotina (32 pacientes) y C-dicloxacillina más amikacina (29 pacientes). Resultados. No hubo diferencias significativas entre los tres grupos en relación a la edad, sexo, factores de riesgo, duración de la cirugía, complicaciones no infecciosas (durante y después del procedimiento quirúrgico) y tasa de mortalidad. Las infecciones globales, respiratorias y de las heridas quirúrgicas tuvieron una tasa más alta en el grupo B. Los días de estancia de la UCI fueron más prolongados en los grupos B y C (p<0.05). Conclusión. La cefuroxima es efectiva en la prevención de la infecciones postoperatorias en cirugía cardiaca

Los azoles en el tratamiento de las micosis profundas y sistémicas / Imidazoles in the treatment of deep and systemic mycosis

Se revisaron las caracteristicas farmacológicas del grupo de los imidazoles: ketoconazol, itraconazol y fluconazol y se compararon sus propiedades, interacciones, efectos secundarios e indicaciones. Se considera que este grupo de medicamentos dada su eficacia, seguridad y facilidad de administración, representan una buena alternativa en el manejo de las micosis profundas y sistémicas