Sex Differences in Temporal Sleep Patterns, Social Jetlag, and Attention in High School Adolescents.

Insufficient sleep and irregular sleep hours are common in adolescents, who experience a delayed sleep phase due to biopsychosocial changes associated with puberty, resulting in later sleep times. However, early morning class hours shorten sleep duration on weekdays. This condition is harmful to cognitive performance, which may be accentuated in girls due to a greater sleep need and less resistance to sleep deprivation. In this study, we evaluated sex differences concerning temporal sleep patterns, social jetlag, and attention in high school adolescents attending morning classes. Students ( n = 146 - F: 73-16.1 ± 0.8 years; M: 73-16.2 ± 0.9 years) completed a Health and Sleep questionnaire, kept a sleep diary for 10 days, which incorporated a Maldonado Sleepiness Scale, and performed a Continuous Performance Task. Girls went to bed earlier and woke up on weekends, and spent more time in bed at night and in 24 h on weekdays and weekends, while they also had a greater irregularity in wake-up times ( p < 0.05). There were no differences between sexes in terms of social jetlag, sleep debt, and sleepiness upon awakening ( p > 0.05). Regarding attention, the girls had a longer reaction time in phasic alertness ( p < 0.01) and a tendency to have fewer errors in selective attention ( p = 0.06). These results persisted when controlled for sleep parameters. Therefore, we suggest that girls have a greater sleep need and less resistance to sleep deprivation, while the differences in attention performance could be due to different strategies, the girls could be making a trade, increasing reaction time in favor of better accuracy, while the boys could be prioritizing a faster response time.

Pediatric tuberculosis in Mexico: A retrospective analysis of 100 patients.

Background: Analyzing the epidemiology and clinical manifestations of pediatric tuberculosis in endemic regions is crucial to meet the goal of ending tuberculosis. The objective was to assess the various clinical scenarios of tuberculosis in a large pediatric cohort in Mexico. Methods: This retrospective study from a pediatric referral center in Mexico included patients diagnosed with tuberculosis from 2012 to 2021. We analyzed clinical data and diagnostic study results, including demographic characteristics, underlying medical conditions, BCG vaccination, clinical presentation, imaging findings, microbiologic data, treatment, and clinical outcomes. Basic descriptive statistics and Chi-squared analysis were performed to summarize the metadata of pediatric patients with different clinical presentations of tuberculosis and evaluate their association with mortality, respectively. Results: A total of 100 patients were included with a mean age of 7.76 years ± 1.49 years. The most prevalent clinical presentation was pulmonary tuberculosis (n = 51). Only 51 patients were immunized with Bacillus Calmette-Guérin vaccine. The most commons symptoms were fever, cough and weight loss. Among patients with meningeal tuberculosis (n = 14), the most common clinical signs were seizures, fever, and vomiting. Cure was achieved in 52 patients, 12 patients died, and 36 continue in treatment. Clinical presentation of tuberculosis (p-value = 0.009) and immunodeficiency (p-value = 0.015) were significantly associated with mortality. Conclusions: Increasing the visibility of tuberculosis is imperative to end this disease. We report relevant clinical data of a large pediatric tuberculosis cohort, stratified by the different forms of disease. A high index of suspicion of tuberculosis is required for a timely diagnosis and treatment initiation, particularly among immunocompromised individuals, in whom mortality is higher.

Total sleep deprivation effects on the attentional blink.

The Attentional Blink (AB) is a phenomenon that reflects difficulty in detecting or identifying the second of two successive targets (T1 and T2) that are presented in rapid succession, between 200-500ms apart. The AB involves indicators of attentional and temporal integration mechanisms related to the early stages of visual processing. The aim of this study was to identify the effects of 24-h of sleep deprivation (total sleep deprivation, TSD) on the attentional and temporal integration mechanisms of the AB. Twenty-two undergraduate students were recorded during five successive days, in these three conditions: baseline (two days), TSD (one day), and recovery (two days). Each day, at around 12:00 h, participants responded to a Rapid Serial Visual Presentation task (RSVP) that presented two targets separated by random intervals from 100 to 1000ms. The attentional mechanisms were assessed by the AB presence, the AB magnitude, and the AB interval, while the temporal integration mechanisms were evaluated by lag-1 sparing and order reversal responses. TSD negatively affected the attentional mechanisms, which is expressed by an overall reduction in performance, an extended AB interval, and a reduced AB magnitude. TSD also negatively affected the temporal integration mechanisms, manifested by an absence of lag-1 sparing and an increase in order reversals. These results suggest that people are still able to respond to two successive stimuli after 24 h without sleep. However, it becomes more difficult to respond to both stimuli because the attentional and temporal integration mechanisms of the AB are impaired.

Changes during the sleep onset process on EEG activity and the components of attention.

The sleep onset process (SOP) happens every time a person falls asleep, regardless of the time of day or if they are doing an activity. Basic cognitive processes, such as attention, differ between wakefulness and sleep. The components of attention - tonic alertness, phasic alertness, selective, and sustained attention - are known to decrease during sleep, however they have not been analyzed during the sleep onset process. This study analyses the state of three of the four components of attention during the sleep onset process through electroencephalographic (EEG) activity and task performance in young people. Nine undergraduate students (18.54±1.24 years old) underwent a control session which was compared to the average of four sleep-inducing sessions. During all sessions, the EEG activity of the subjects was recorded to assess the effect of the SOP on electroencephalographic activity while they answered a continuous performance task (CPT) to assess the effect of the SOP on the components of attention. Comparisons of the EEG recordings of the control and the sleep inducing sessions demonstrated that there is lower activity in fast beta, as well as a higher theta and delta activity right before the sleep onset. There was a decrease in tonic alertness, phasic alertness, and selective attention. This study shows that there is an increase in EEG slow activity and a decrease in fast activity, as well as in attentional capacity during the SOP. This decrease can become a safety hazard since it could happen while performing daily activities.

Changes in sleep habits during the lockdown for the COVID-19 pandemic in the population and people attending a morning or an afternoon shift in Monterrey, Mexico.

To fight the Covid-19 pandemic, most countries implemented a lockdown that involved restricting the activity and confining the population to their homes. The objective of this paper is to analyze the impact of the lockdown on sleep in people from the population of Monterrey, Mexico, and people attending a morning or afternoon work or study shift after more than a month adaptation period. Participants were 861 residents from Monterrey, Mexico, who completed an anonymous 20-minute web-based survey. The survey asked for information about sleep habits both before and during the lockdown. In Mexico, a national lockdown was declared on March 23rd, 2020. Data collection began 38 days after the start of the lockdown, from April 30th to May 23rd, 2020, allowing enough time for the participants to adjust to the new conditions. The lockdown affected the sleep of the population, producing a phase delay of the sleep-wake cycle, a reduction of sleep duration, as well as an increase in sleep latency and in time awake during night sleep, resulting in a reduction of sleep efficiency. People attending an afternoon shift also showed a phase delay and a reduction in sleep quality during the lockdown. In conclusion, the lockdown produced a delay of sleep and a reduction of sleep quality of the population, even in people with an afternoon shift. It is necessary to design and implement better strategies in the fight against the pandemic, without compromising the wellbeing of the population.

Comparative analysis of sleep patterns and attention components in high school and college adolescents.

Adolescence is a phase with physiological and behavioral changes. One of them occurs in the sleep-wake cycle pattern, manifested by a phase delay. However, morning school start time can decrease sleep duration during weekdays, impairing adolescent cognitive performance and well-being. Adolescents of different ages and educational level might suffer the impact of academic demand on sleep-wake cycle and cognition differently. Thus, the aim of this study is to compare the sleep habits and quality, sleepiness upon awakening and attention components among adolescents in the first years of high school and college. 71 adolescents participated in the study (45 girls and 26 boys), 44 enrolled in high school morning classes (G1 - 15.5±0.7 years), from a private school, and 27 college students enrolled in morning classes (G2 - 18.8±1.04 years), from biosciences courses from a public institution. The groups did not differ in bedtime, get up time, time in bed and sleep irregularity. However, both groups showed differences according to the day of the week, bedtime and get up time became later and time in bed extended on weekends. G1 presented worse sleep quality and regarding attention, showed higher percentage of omissions in all components and worse performance in sustained attention (ANOVA, p<0.05). The poorer sleep quality of high school adolescents and reduced attention may have a negative effect on school performance. Additional studies are needed to investigate the causes of these differences between these two educational levels.

Sleep deprivation effects on basic cognitive processes: which components of attention, working memory, and executive functions are more susceptible to the lack of sleep?

INTRODUCTION: Sleep deprived people have difficulties to perform daily activities. Their performance depends on three basic cognitive processes: attention, working memory, and executive functions. OBJECTIVES: The aim of this study was to identify which specific components of these cognitive processes are more susceptible to a 24-h sleep deprivation period. MATERIAL AND METHODS: Participants were 23 undergraduate students assigned to one of two groups: a control group (n=11, age=18.73±1.62 years) and a sleep deprivation group (n=12, age=18.08±1.16 years). After sleeping freely, control group participants performed a continuous performance task to evaluate the components of attention, a phonological and a visuospatial tasks to record these components of working memory, and a Stroop-like task to assess cognitive inhibition and flexibility, two components of executive functions, at noon for 3 days. Whereas, the sleep deprivation group participants performed the same tasks at noon: after sleeping freely for one night, after a 24-h sleep deprivation, and after one recovery night. RESULTS: After the sleep deprivation, participants had a significant reduction in tonic alertness, selective and sustained attention, components of attention; and in cognitive inhibition, component of executive functions. CONCLUSION: A 24-h sleep deprivation period reduces several specific components of the basic cognitive processes, which are crucial for performing many everyday activities, thus increasing the risk of errors and accidents.

Daily light exposure, sleep-wake cycle and attention in adolescents from different urban contexts.

OBJECTIVE: to compare daily light exposure, activity-rest rhythm, sleep-wake cycle (SWC) and attention in Brazilian students living in different levels of urbanization. METHODS: 115 adolescents (74 girls), aged 14-18 years (mean 15.5 ± 0.7 years), from the first years of high school have participated. The SWC was evaluated by actimetry and a Sleep Diary for 10 days. Besides, the "Health and Sleep" Questionnaire, the Morningness and Eveningness Scale for adolescents, the Pittsburgh Sleep Quality Index, and the Pediatric Daytime Sleepiness Scale were answered. Attention was assessed by a Continuous Performance Task. RESULTS: In the less urbanized region, there were a greater exposure to light during the day accompanied by a higher proportion of morning-types and less occurrence of excessive daytime sleepiness. Otherwise, in the more urbanized region, adolescents showed a trend to sleep less in weekdays and presented more irregularity in sleep duration between weekdays and weekend, with 83 ± 15% of sleep efficiency, 01:04 ± 1:30 h of WASO and 7 ± 6.7 awakenings per night on the weekdays, suggestive of poor sleep quality. Despite of this, they showed better attentional performance: more correct responses (tonic and phasic alertness, and sustained attention) and less omissions (for all components). Regardless of the degree of urbanization, there was partial sleep deprivation, irregular sleep schedules and poor sleep quality in adolescents. CONCLUSIONS: The daily light exposure and activity-rest profiles, SWC and attention in adolescents varied according to the degree of urbanization. Besides, the negative impacts of early school starting times leading to sleep deprivation, irregular sleep times and poor sleep quality were observed irrespective of the degree of urbanization, reinforcing that the early school starting time at morning is a strong temporal challenge for teenagers, having negative impacts on cognition and academic performance.

Circadian Rhythms in Attention.

Attention is a cognitive process crucial for human performance. It has four components: tonic alertness, phasic alertness, selective attention, and sustained attention. All the components of attention show homeostatic (time awake, sleep deprivation) and circadian (time of day) variations. The time course of the circadian rhythms in attention is important to program work and school-related activities. The components of attention reach their lowest levels during nighttime and early hours in the morning, better levels occur around noon, and even higher levels can be observed during afternoon and evening hours. However, this time course can be modulated by chronotype, sleep deprivation, age, or drugs. Homeostatic and circadian variations have also been found in other basic cognitive processes (working memory and executive functions), with a time course similar to that observed for attention. Data reviewed in this paper suggests the need to consider circadian rhythms, age, and chronotype of the person, when programming schedules for work, study, school start time, school testing, psychological testing, and neuropsychological assessment.

Effects of a co-culture of marine algae and shrimp (Litopenaeus vannamei) on the growth, survival and immune response of shrimp infected with Vibrio parahaemolyticus and white spot virus (WSSV).

In aquaculture, fighting infectious diseases is a necessity. This study measured the immuno-stimulating effect of live macroalgae consumption on Litopenaeus vannamei against Vibrio parahaemolyticus and WSSV infection in two independent bioassays. Shrimps and macroalgae were cultivated in a co-culture with two species of macroalgae separately (Gracilaria vermiculophylla and Dictyota dichotoma), and later, shrimp were infected with V. parahaemolyticus. In another bioassay, shrimp and macroalgae (G. vermiculophylla, D. dichotoma and Ulva lactuca) were grown and subsequently infected with WSSV. For both bioassays, survival after 120 h was determined, the total hemocyte count (TCH) was measured and the activity of superoxide dismutase (SOD) and catalase (CAT) in tissue were measured. The results indicate that the use of macroalgae in co-culture with L. vannamei provides a nutritional benefit that achieves higher growth than the control organisms, as well as improvements of the ammonium concentration and immune response after infection with V. parahaemolyticus and WSSV. A better immune response was obtained in organisms cultured with macroalgae in both bioassays at a ratio of 1.6-1.9 for organisms infected with bacteria and 1.4 to 1.6 times for organisms infected with the virus. In turn, the enzymatic activity of SOD and CAT were higher in the treated organisms relative to the controls in both experiments.

Circadian and homeostatic modulation of the attentional blink.

An important property of attention is the limitation to process new information after responding to a stimulus. This property of attention can be evaluated by the Attentional Blink (AB), a phenomenon that consists of a failure to detect the second of two targets when the interval between them is 200-500 ms. The aim of the present work is to determine the possible existence of time awake (homeostatic changes) and time of day (circadian rhythm) variations in the AB. Eighteen undergraduate students, 11 men and 7 women, age = 18.06 ± 1.16 years, participated voluntarily in this research. They were recorded in a constant routine protocol during 29 h, in which rectal temperature was recorded every minute, while subjective sleepiness and responses to a Rapid Serial Visual Presentation (RSVP) task, to measure the AB, were recorded every hour. Homeostatic and circadian variations in all parameters of the RSVP task were observed, including changes in the capacity to process a new stimulus (Target 1 accuracy), a second stimulus occurring in a short interval after the first (Target 2 accuracy at lag 2, 200 ms) and to process another successive independent stimulus (Target 2 accuracy at lag 8, 800 ms). The acrophase of these parameters occurred with a phase delay of 2 h compared to the circadian rhythm of rectal temperature. The AB magnitude, an index of the AB, showed a decline with time awake, but no variations with time of day. In conclusion, there are homeostatic and circadian variations in the capacity to process any incoming information, especially in tasks with brief duration stimuli presented at a high frequency.

Comorbidities and antimicrobial resistance in urological outpatients with positive urine culture / Resistencia bacteriana y comorbilidades presentes en pacientes urológicos ambulatorios con urocultivos positivos

Background: The urinary tract infections are the third cause of infections in Mexico. The inappropriate use of antibiotic has generated the presence of multidrugresistant bacteria. Objective: To identify the bacterial resistance patterns of the hospital and to detect the present comorbidities that can modify the evolution of urinary tract infection for proper empirical management. Methods: Non-comparative cross-sectional study, positive urine cultures were reviewed in the period from December 2015 to May 2016, in outpatients of urology in the hospital. The obtained growth, bacterial resistance and the comorbidities of each patient were analyzed. Results: 190 urine cultures were included. The most frequent bacterium was Escherichia coli. Greater general antibiotic resistance was detected to ceftazidime (91.5%), quinolones (> 65%) and trimethoprim / sulfamethoxazole (58%). The general multiresistance was 66.3%. The antibiotics that showed greater sensitivity were: amikacin, imipenem, nitrofurantoin, meropenem and piperacillin / tazobactam. The most frequent comorbidities were diabetes mellitus, previous use of antibiotics for urinary tract infection and prostatic hyperplasia. Conclusion: In patients with urinary tract infection in the hospital, the empirical use of nitrofurantoin and amikacin is recommended. Quinolones and trimethoprim / sulfamethoxazole have a high resistance index.

Introducción: las infecciones de vías urinarias son la tercera causa de morbilidad por infecciones en México. El uso indiscriminado de antibióticos ha generado la aparición de bacterias multiresistentes. Objetivo: identificar los patrones de resistencia bacteriana del hospital y detectar las comorbilidades presentes que pueden alterar el curso de una infección urinaria, para el manejo empírico adecuado. Métodos: estudio transversal no comparativo, se revisaron los urocultivos positivos en el período diciembre de 2015 a mayo de 2016, en pacientes ambulatorios de urología del hospital. Se analizó crecimiento obtenido, resistencia bacteriana y las comorbilidades de cada paciente. Resultados: se incluyeron 190 urocultivos. La bacteria más frecuente fue Escherichia coli. Se detectó mayor resistencia antibiótica general a ceftazidima (91.5%), quinolonas (> 65%) y trimetoprim/sulfametoxazol (58%). La multirresistencia general fue de 66.3%. Los antibióticos que demostraron mayor sensibilidad fueron: amikacina, imipenem, nitrofurantoína, meropenem y piperacilina/tazobactam. Las comorbilidades más frecuentes fueron diabetes mellitus, uso previo de antibióticos para infección de vías urinarias e hiperplasia prostática. Conclusiones: en los pacientes con infección de vías urinarias del hospital, se recomienda el uso empírico de nitrofurantoína y amikacina. Las quinolonas y el trimetoprim/sulfametoxazol tienen un alto índice de resistencia.

Effect of temperature and salinity on larval survival and development of Litopenaeus vannamei / Efecto de temperatura y salinidad sobre la supervivencia y desarrollo larval de Litopenaeus vannamei

ABSTRACT Objective. The combined effect of salinity (25, 30, 35, and 40psu) and temperature (25, 30, and 35oC) was evaluated on survival and development from nauplii V (NV) larvae until postlarvae (PL1) of Litopenaeus vannamei. Materials and methods. Four replicates were applied to each combination of salinity and temperature. The larvae were placed in 12 L beakers a density of 100larvae/L. Salinity was increased dissolving commercial salt without iodine, into marine water, whereas fresh filtered tap water was used to decrease the salinity from seawater. The NV were adapted at 35psu and 30°C during 30 minutes. Thereafter, were transferred at each experimental combination of salinity and temperature. Every 24 h, samples of larvae were obtained to determine in vivo their stage of development and survival. All data were analyzed using a two-way ANOVA. Results. Survival and larval development were significantly (p<0.05) affected by salinity, temperature and interaction of both factors. Maximum ultimate survival to PL1 was obtained at 30°C and 30psu (82.2%) followed by 30 and 35°C at 25psu (71.5 y 71.6%). The highest development at PL1 was found at 30°C and 30psu (6.76). Larval development during experiment was lower at 25°C as compared to 30 and 35°C, regardless of the salinity levels. Conclusions. The most adequate conditions for survival and larval development were obtained between 30-35°C and 25-30psu.

RESUMEN Objetivo. Analizar el efecto combinado de salinidad (25, 30, 35 y 40 ups) y temperatura (25, 30 y 35°C) sobre la supervivencia y el desarrollo de larvas nauplio V (NV) hasta postlarvas (PL1) de Litopenaeus vannamei. Materiales y métodos. Los experimentos se realizaron por cuadriplicado por cada combinación de salinidad y temperatura. Las larvas se mantuvieron en acuarios de 12 L a una densidad de 100larvas/L. La salinidad se incrementó disolviendo sal granulada libre de yodo, a partir de agua de mar, mientras que para alcanzar las salinidades menores se utilizó agua dulce filtrada. Los NV aclimatados a 35ups y 30°C durante 30 minutos fueron transferidos a cada combinación experimental de salinidad y temperatura. Cada 24 h, se obtuvieron muestras de larvas para determinar in vivo su etapa de desarrollo y supervivencia. Los datos fueron analizados por un ANOVA de dos vías. Resultados. La supervivencia y el desarrollo larval fueron significativamente afectadas por la salinidad, temperatura y su interacción (p<0.05). La máxima supervivencia final a PL1 se obtuvo a 30°C y 30ups (82.2%), seguido por 30 y 35°C a 25ups (71.5 y 71.6%). El desarrollo más alto a PL1 fue encontrado a 30°C y 30ups (6.76). El desarrollo larval durante el experimento fue más bajo a 25°C en comparación con 30 y 35°C, independientemente de los niveles de salinidad. Conclusiones. Las condiciones más adecuadas para la supervivencia y desarrollo larval se obtuvieron entre 30-35°C y 25-30ups.

Effects of methanolic macroalgae extracts from Caulerpa sertularioides and Ulva lactuca on Litopenaeus vannamei survival in the presence of Vibrio bacteria.

Macroalgae are potentially excellent sources of highly bioactive secondary metabolites that are useful for the development of new functional ingredients. This study was conducted to determine whether methanolic extracts from Caulerpa sertularioides and Ulva lactuca macroalgae might be possible alternatives for the prevention of shrimp vibriosis, which is caused by Vibrio parahaemolyticus and Vibrio alginolyticus. Macroalgae extracts prepared with methanol as the solvent were evaluated for antibacterial activity with the microplate method. The extracts' effects on the mortality of juvenile Litopenaeus vannamei were evaluated at doses of 150 and 300 mg L(-1). Two independent assays for V. parahaemolyticus and V. alginolyticus were performed. The methanolic extract of C. sertularioides exhibited activity against V. parahaemolyticus and V. alginolyticus, and it had minimal inhibitory concentrations of <1000 and < 1500 µg mL(-1), respectively. L. vannamei mortality in the presence of both The methanolic extract of C. sertularioides exhibited activity against V. parahaemolyticus and V. alginolyticus, and it had minimal inhibitory concentrations of <1000 and <1500 µg mL(-1), respectively. and V. alginolyticus bacteria significantly decreased after treatment with 300 mg L(-1) C. sertularioides methanolic extract.

Effect of the diet traditional and non-traditional on the respiration and excretion in larvae of white shrimp Litopenaeus vannamei / Efecto de la dieta tradicional y no tradicional en la respiración y excreción de larvas de camarón blanco Litopenaeus vannamei

Objective. It was studied the respiration and ammoniacal excretion of zoeas and mysis of Litopenaeus vannamei fed with the diet used traditionally (of microalgae and nauplios of Artemia) and another alternative (not traditional) of microalgae with rotifers. Materials and methods. After four hours the oxygen consumption and ammonia excretion in BOD bottles with 60 larvae (closed respirometers) was estimated. The concentrations of O2 and NH4+ were measured with an electrode polarográfico in the first case and with the indophenol blue technique for the second. Results. In zoea, oxygen consumption increased with development and showed statistical differences (p=0.023). In mysis, the oxygen consumption were significance in the traditional diet, whereas no differences were alternative (p=0.003). In both stages for the ammoniacal excretion increased development stage and there were detected statistical difference (p<0.001), although to the diets were not noticed significant differences. Conclusions. A higher energy absorption for zoea (I, II y III) what mysis (I, II y III) larvae was obtained, this is likely an interaction between rates of respiration and excretion caused by variations in the efficiency of absorption by the larvae. The weights obtained in both larvae were not supplied with differences between diets.

Objetivo. Se analizó la respiración (O2) y excreción amoniacal (NH4+) en larvas zoea y mysis de camarón blanco Litopenaeus vannamei, alimentadas con las dietas tradicionales (microalgas y nauplios de Artemia) y no tradicionales (microalgas y rotíferos). Materiales y métodos. A las cuatro horas de experimentación se estimó el consumo de oxígeno y la excreción de amonio en botellas BOD con 60 larvas (respirómetros cerrados). La concentración de O2 se midió con un electrodo polarográfico y la NH4+ se determinó con la técnica de azul de Indofenol. Resultados. En zoea, el consumo de oxígeno incrementó con el desarrollo y se presentaron diferencias estadísticas (p=0.023). En mysis, los consumos de oxígeno presentaron una significancia entre la dieta tradicional, mientras en la alternativa no se obtuvieron diferencias (p=0.003). La excreción en ambos estadios larvales aumentó con la fase y se detectaron diferencias estadísticas (p<0.001), aunque no se registraron diferencias significativas en las larvas respecto a las dietas suministradas. Conclusiones. Se obtuvo una absorción de energía superior para las zoea (I, II y III) que mysis (I, II y III), esto probablemente a una interacción entre las tasas de respiración y de excreción provocada por variaciones en la eficiencia de absorción de las larvas. Los pesos obtenidos en ambas larvas no resultaron con diferencias entre las dietas suministradas.

Sleep-wake habits and circadian preference in Mexican secondary school.

OBJECTIVE: The current study aimed to determine the differences between sleep-wake habits and circadian preference in Mexican adolescents attending classes at a morning shift or an afternoon shift. METHODS: The sample consisted of 568 students of a secondary school in Reynosa, northeastern Mexico, of whom 280 were boys and 288 were girls (mean age 14.08 ± 0.72 years, age range 13-16 years). In the morning shift, 287 students attend classes on a schedule from 7:30 to 13:00 and the afternoon shift, 281 students, on a schedule from 13:20 to 19:00. Students completed a general information questionnaire, the Sleep Timing Questionnaire and the Spanish version of the Morningness-Eveningness Questionnaire. RESULTS: The adolescents who attended the morning shift had earlier bedtime and waking time, but shorter sleep duration than those who attended the afternoon shift. Those oriented to eveningness had later bedtime, waking time, and a shorter sleep duration than those oriented to morningness. Two interactions were found between school shift and chronotype. First, with regard to waking time during weekdays, students who attended the afternoon shift and were oriented to eveningness woke up later than those who attended the morning shift and were oriented to eveningness; during weekdays, there were no differences between the waking time of morning-type and evening-type students who attended the morning shift. Second, with regard to sleep duration on weekdays, students who attended the morning shift and were oriented to eveningness had the shortest sleep duration. Furthermore, there were no differences between sleep duration on weekdays in evening-type and morning-type students of the afternoon shift. CONCLUSION: Adolescents who attend classes in the morning shift and are oriented to eveningness are the most sleep deprived. Those who attend the afternoon shift will have optimal sleep duration, regardless of their circadian preference.

Effects of sleep reduction on the phonological and visuospatial components of working memory.

Sleep reduction impairs the performance of many tasks, so it may affect a basic cognitive process, such as working memory, crucial for the execution of a broad range of activities. Working memory has two storage components: a phonological and a visuospatial component. The objective of this study was to analyze the effects of sleep reduction for 5 days on the storage components of working memory. Thirteen undergraduate students (18.77±2.20 years of age), 5 men and 8 women, responded two N-Back tasks (auditory and visual), with three sections each (0-Back, 1-Back, and 2-Back). These tasks were performed at 13:00 h under the following conditions: before sleep reduction (control; C); on the first (SR1), fourth (SR4), and fifth (SR5) days of sleep reduction (4 h of sleep per night); and one day after they slept freely (recovery, R). Sleep reduction produced a decrement in accuracy on the auditory 2-Back section the fifth day of sleep reduction (C=87.86±13.35%; SR5=74.76±16.37%; F=14.57, p<0.01). In the visual 2-Back section accuracy decreased (C=88.10±9.95%; SR1=82.45±11.57%; SR5=77.76±14.14%; F=10.80, p<0.05), and reaction time increased (C=810.02±173.96 ms; SR1=913.51±172.25 ms; SR5=874.78±172.27 ms; F=10.80, p<0.05) on the first and fifth day of sleep reduction. In conclusion, five days of sleep reduction produces a decrease in the phonological and visuospatial storage components of working memory, which may interfere with processing verbal information and solving problems that require spatial analysis.

Evaluation of the Light-Cycler® SeptiFast Test in Newborns With Suspicion of Nosocomial Sepsis.

BACKGROUND: Nosocomial sepsis (NS) in newborns (NBs) is associated with high mortality rates and low microbial recovery rates. To overcome the latter problem, new techniques in molecular biology are being used. OBJECTIVES: To evaluate the diagnostic efficacy of SeptiFast test for the diagnosis of nosocomial sepsis in the newborn. MATERIALS AND METHODS: 86 blood specimens of NBs with suspected NS (NOSEP-1 Test > 8 points) were analyzed using Light Cycler SeptiFast (LC-SF) a real-time multiplex PCR instrument. The results were analyzed with the Roche SeptiFast Identification Software. Another blood sample was collected to carry out a blood culture (BC). RESULTS: Sensitivity (Sn) and specificity (Sp) of 0.69 and 0.65 respectively, compared with blood culture (BC) were obtained for LC-SF. Kappa index concordance between LC-SF and BC was 0.21. Thirteen (15.11%) samples were BC positive and 34 (31.39%) were positive with LC-SF tests. CONCLUSIONS: Compared with BC, LC-SF allows the detection of a greater number of pathogenic species in a small blood sample (1 mL) with a shorter response time.

Circadian and homeostatic variation in sustained attention.

Human performance is modulated by circadian rhythms and homeostatic changes. Changes in efficiency in the performance of many tasks might be produced by variation in a basic cognitive process, such as sustained attention. This cognitive process is the capacity to respond efficiently to the environment during prolonged periods (from minutes to hours). There are three indices of sustained attention: general stability of efficiency, time on task stability, and short-term stability. The objective of this work was to analyze circadian and homeostatic influences on the indices of sustained attention. Participants were nine undergraduate female student volunteers (mean age 17.67 yrs, SD = 1.00, range 16-19 yrs) who attended school from 07:00-13:30 h, Monday to Friday. They were assessed while adhering to a modified 28 h constant-routine protocol during which feeding, room temperature, motor activity, and room illumination were controlled. Rectal temperature was recorded each minute, and indices of sustained attention were assessed hourly through a continuous performance task (CPT). General stability was measured as standard deviation of correct responses and reaction time, time on task stability was measured as the linear regression of correct responses and reaction time throughout the task, and short-term stability was measured as hit runs and error runs. Rectal temperature showed circadian variation; subjective somnolence and tiredness increased, while general performance and all indices of sustained attention declined throughout the 28 h recording session. General stability exhibited circadian variation, whereas time on task did not. Short-term stability showed circadian variations in short-error runs, long-error runs, and short-hit runs, but long-hit runs did not. There was a 26 sec short interval at the beginning of the task, characterized by a very high efficiency level of performance. Execution during this safe period was not affected by time awake and did not show circadian variation. Overall, these results suggest a dissociation of the effects of circadian and homeostatic factors on the indices of sustained attention. General stability, short- and long-error runs, and short-hit runs were modulated by both a homeostatic factor and a circadian effect, while long-hit runs and time on task stability were modulated only by a homeostatic factor and did not show circadian variation. There was also a 26 sec "safe period" that seems to be independent of circadian and homeostatic influences. These results suggest that performance at work deteriorates at the end of a shift due to a decrease in general stability, an increase in error runs, decrease of long-hit runs, and decline with time on task. Night shiftworkers are exposed to an additional deterioration of performance during the nighttime due to a decrease in general stability and an increase in error runs.

Efectos psicofisiológicos de la eliminación del horario de verano en una población nunca antes expuesta a éste / Psychological effects of daylight saving time elimination in a population never before exposed to it

El horario de verano consiste en adelantar el reloj una hora, y se introdujo por primera vez en cuatro estados del noreste de nuestro país, del 3 de marzo al 30 de octubre de 1988. El objetivo del presente estudio es analizar los efectos que provoca la eliminación del horario de verano (retrasar el reloj una hora) en una población nunca antes expuesta a este tipo de cambio. Se realizó un registro diario del inicio, de la terminación y de la latencia del dormir en 19 trabajadores durante 26 días, 9 días antes y 17 días después de la eliminación del horario de verano. Además, al inicio y al final del estudio, se aplicaron los siguientes cuestionarios: Evaluación de trastornos del dormir, Escala de Depresión de Zung y Autoevaluación de la Fase Circadiana. Después de la eliminación del horario de verano, todos los trabajadores despertaron más tarde. doce de ellos se acostaron más tarde (de 23:04 A 24:04 hd, horas: minutos, hd=hora del día) y durmieron menos (de 8:01 a 7:38 h), pero tuvieron menos cansancio al despertar. Las otras siete personas siguieron acostándose aproximadamente a la misma hora (de 23:19 a 23:40 hd), pero disminuyeron su latencia y sus dificultades para empezar a dormir. Estos resultados tienden a apoyar la hipótesis de que la eliminación del horario de verano (retraso de una hora), produce menos problemas sobre el sistema circadiano que su introducción (adelanto de una hora)