The 1991 explosive Hudson volcanic eruption as a geochronological marker for the Northern Antarctic Peninsula.

It is estimated that the explosive Hudson volcano eruption in Southern Chile injected approximately 2.7 km3 of basalt and trachyandesite tephra into the troposphere between August 8-15, 1991. The Hudson signal has been detected in Antarctica at the eastern sector and in South Pole snow. In this work, we track the Hudson volcanic plume using a dispersion model, remote sensing, and a re-analysis of a high-resolution ice core analysis from the Detroit Plateau in the Antarctic Peninsula and sedimentary records from shallow lakes from King George Island (KGI). The Hudson eruption imprint in these records is confirmed by using a weekly resolved aerosol concentration database from KGI demonstrating that the regional impact of Hudson eruption predominates over the Mount Pinatubo/Phillippines volcanic signal, dated from June 1991, in terms of particulate matter depositions. The aerosol elemental composition of Ca, Fe, Ti, Si, Al, Zn, and Pb increases from 2 to 3 orders of magnitude in background level during the days following the eruption of the Hudson volcano.

Impact of social isolation on the level of physical activity in young Brazilian athletes caused by COVID-19.

BACKGROUND: Social detachment to prevent the spread of the COVID-19 pandemics in the year 2020 can significantly contribute to the physical inactivity of citizens worldwide. The study aimed to analyze the level of physical activity by identifying the training methods used during the social isolation resulting from the COVID-19 pandemic. METHODS: Sixty-eight Brazilian athletes (both sexes, 14.7±1.68 years) answered and adapted the International Physical Activity Questionnaire (I-PAQ) through an online platform. Participants were asked to report their level of physical activity before and during the period of social distance. RESULTS: According to our results, 67.7% of the interviewed athletes said they were able to adapt their sports training to the isolation environment under the guidance of a distance physical education professional. Only 4.38% of the sample was not training under such supervision and, therefore, inactive. Among the activities performed in the isolation environment, calisthenics was the primary practice (effect size: ƒ2=0.50, P<0.0001) and the sport practiced at home was the secondary practice (effect size: ƒ2=0.27, P=0.004). During the pandemic, the training hours of athletes reduced significantly from ~3h to ~1h per day (effect size: 1.74, P<0.0001), as well as the perceived intensity decreased from "high" to "moderate" (effect size: 1.38, P<0.0001). The weekly training frequency decreased from ~6 to 7 days to ~3 to 5 days (effect size: 0.40, P=0.03). CONCLUSIONS: Despite the social distance and the reduced pace of training, the young Brazilian athletes analyzed managed to remain physically active during the COVID-19 pandemic.

Evaluation of Training with Elastic Bands on Strength and Fatigue Indicators in Paralympic Powerlifting.

BACKGROUND: Variable resistance training has recently become a component of strength and conditioning programs. OBJECTIVE: This randomized counterbalanced cross-over study aimed to investigate the use of elastic bands (EB) and the traditional method (TRAD) and force indicators in a training session. METHODS: 12 Paralympic athletes (age: 28.60 ± 7.60 years) participated in this three-week study. In the first week, the participants were familiarized with EB and TRAD and were tested for maximal repetition (1-RM). The research occurred in weeks 2 and 3, which included the pre-post training, during which the following measures were extracted: maximum isometric force (MIF), the peak torque (PT), rate of force development (RFD), fatigue index (FI), and time to MIF (Time). The athletes performed two tests, EB and TRAD, separated by a one-week interval. RESULTS: Significant differences were found between the pre- and post-test for 1RM (p = 0.018, η2p = 0.412), MIF (p = 0.011, η2p = 0.415), PT (p = 0.012, η2p = 0.413), and RFD (p = 0.0002, η2p = 0.761). With the use of EB, there was a difference in RFD between TRAD before and EB after (p = 0.016, η2p = 0.761). There were significant differences in the before and after for FI between TRAD and EB (p < 0.001) and for Time (p < 0.001), indicating that training with the use of elastic bands promotes overload, characterized by increased fatigue and decreased strength. CONCLUSIONS: Training with EB did not decrease 1RM, PT, MIF or RFD, however, there was an increase in fatigue and time to reach MIF when compared to the method with fixed resistance.

Effects of Ibuprofen Use on Lymphocyte Count and Oxidative Stress in Elite Paralympic Powerlifting.

BACKGROUND: Paralympic Powerlifting (PP) training tends to promote fatigue and oxidative stress. OBJECTIVE: To analyze the effects of ibuprofen use on performance and oxidative stress in post-training PP athletes. METHODOLOGY: Ten national level PP athletes (age: 27.13 ± 5.57) were analyzed for oxidative stress in post-training. The study was carried out in three weeks, (1) familiarization and (2 and 3) evaluated the recovery with the use of a placebo (PLA) and ibuprofen (IBU), 800 mg. The Peak Torque (PT), Torque Development Rate (TDR), Fatigue Index (FI), reactive substances to thiobarbituric acid (TBARS) and sulfhydryl groups (SH) were evaluated. The training consisted of five sets of five repetitions (80-90%) 1-Repetition Maximum (1-RM) in the bench press. RESULTS: The IBU showed a higher PT (24 and 48 h, p = 0.04, ɳ2 p = 0.39), a lower FI (24 h, p = 0.01, ɳ2p = 0.74) and an increased lymphocyte count (p < 0.001; ɳ2p = 4.36). There was no change in oxidative stress. CONCLUSIONS: The use of IBU provided improvements in strength and did not protect against oxidative stress.

Relationship of Biological Maturation with Muscle Power in Young Female Athletes.

There is still no consensus on how biological maturation (BM) affects the muscle power of upper and lower limbs in young people. The objective was to verify associations between BM and muscle power, as well as to compare the muscle power of upper (ULP) and lower limbs (LLP) among young athletes in different stages of BM. The sample consisted of 79 female athletes (10.9 ± 1.11 years old). Regarding BM, the sample was divided into three groups: delayed BM, synchronized BM, and accelerated BM. BM was identified by subtracting chronological age from bone age (BA). BA was measured by a mathematical model based on anthropometry. The muscular power of the upper limbs was analyzed by the medicine ball launch test, and that of the lower limbs was analyzed by the countermovement jump on a force platform. BM and BA correlated with ULP (BA: r =0.74; BM: r =0.65) and LLP (BA: r = 0.50; BM: r =0.41). In the comparisons of the tests of ULP and LLP, the groups with synchronized and accelerated BM were superior to the group with delayed BM. The advance of BM is associated with the ULP and LLP, as well as the advance of the BM affects muscle power in young female athletes. This occurs due to the increase in body mass resulting from the advancement of BM, which may favor the predominance of lean body mass, assisting in the production of muscle strength.

Influence of Healthy Habits Counseling on Biochemical and Metabolic Parameters in Children and Adolescents with HIV: Longitudinal Study.

We analyze the influence of dietary counseling and physical activity on biochemical and metabolic parameters in children and adolescents with HIV. A longitudinal experimental study, including three analyses: At the beginning, 4th month, and 8th month. A sample of 18 subjects with HIV of both sexes, mean age 10.4 ± 4.50 years. Usual food intake (24 h recall and food intake marker), level of habitual physical activity, biochemical parameters, resting metabolic rate, as well as body composition (dual-energy X-ray absorptiometry), biological maturation, and anamnesis with clinical data and socioeconomic were evaluated. There was an effect of time on the reduction of blood glucose and triglycerides and the resting metabolic rate. There was a significant increase in fruit consumption throughout the study. The consumption of soft drinks decreased when comparing analysis periods 1 and 2, however, it increased again in analysis period 3. There was no significant effect of time on the set of variables related to a food recall. Counseling healthy habits and regular clinical follow-up were relevant for improving biochemical parameters (glucose, triglyceride, HDL cholesterol), maintaining the resting metabolic rate, increasing fruit consumption, and decreasing the consumption of soft drinks, in part of the time, of children and adolescents with HIV. Finally, we emphasize that counseling positively influenced healthy habits, and these, in turn, improved health-related parameters.

The influence of biological maturation and neuromuscular performance on peak bone mineral density in children.

BACKGROUND: The growth and development cycle of the adult is characterized by substantial changes in physical size and maturity, and is controlled by the simultaneous influence of genetic components and the environment. Changes in the development of bones, muscles and adipose tissue are among the most important aspects of adolescent physical development. The aim of this research was to examine the correlation between bone mineral density (BMD) and neuromuscular performance in children at different stages of maturation. METHODS: The study included 31 participants of both sexes (11.7±1.89 years). Body composition was assessed through bone densitometry using an energy duo X-ray source. The neuromuscular performance of the upper limbs was analyzed by the medicine ball hand grip and throwing tests. The lower limbs by the vertical counter-motion jump test, and skeletal maturation was analyzed by bone age. Maturation was used as an effect control between the association of BMD and neuromuscular performance. RESULTS: The results demonstrated significant associations between the performance of upper (P<0.0001) and lower (P=0.01) limbs and BMD. On inter-group comparison for only the accelerated maturational stage, male participants had greater BMD than female participants (P=0.001; effect size 3.13). Regarding the maturational stages, male participants in the accelerated maturational stage demonstrated higher BMD than those in the normal and delayed maturational stages (P=0.04; effect size 3.10), whereas female participants did not demonstrate significant differences in BMD accumulation. CONCLUSIONS: BMD has a strong correlation with the neuromuscular performance of upper and lower limbs of children of both sexes.

Can the Neuromuscular Performance of Young Athletes Be Influenced by Hormone Levels and Different Stages of Puberty?

BACKGROUND: Endocrine mechanisms can be a determining factor in the neuromuscular performance of young athletes. OBJECTIVE: The objective of the present study was to relate maturational and hormonal markers to neuromuscular performance, as well as to verify whether young athletes with different testosterone levels show differences in muscle strength. METHODS: The sample consisted of 37 young male Brazilian athletes (11.3 ± 0.94 years) who were members of a sports initiation project. Hormonal markers were analyzed biochemically by blood samples, and maturation markers by mathematical models based on anthropometry. Body composition was verified by tetrapolar bioimpedance. The performance of upper and lower limb strength and body speed were analyzed. RESULTS: Hormonal and maturational markers were related to neuromuscular performance (p < 0.05). Young people with higher testosterone levels showed higher muscle strength (p < 0.05). Artificial neural networks showed that testosterone predicted the performance of upper limbs by 49%, and maturation by 60%. Maturation foreshadowed the performance of lower limbs by 30.3%. CONCLUSION: Biological maturation and hormonal levels can be related to neuromuscular performance, and young people with higher testosterone levels show superior muscle strength in relation to the others.

Characterizing the temperature response of a Hg-Cd-Te camera for field applications.

Hg-Cd-Te (MCT) cameras can be used to analyze the thermal emission or the infrared reflective response of physical systems. However, measurements performed with this instrument need to be corrected for the thermal emission from the environment surrounding the camera. In this work we analyzed this effect under conditions typically met in field applications, when environmental temperature variations are common. The dark current signal on a Xeva MCT 320 CL TE4 camera was studied as a function of ambient temperature and the integration time used for image acquisition. The MCT sensor at the focal plane was kept at a constant nominal temperature of 210 K by a thermoelectric cooler unit throughout the experiment. Integration times for data acquisition varied between 2.0 to 12.0 ms. The camera body temperature was monitored within ±0.2°C, ranging from about 17.0°C to 27.0°C. The camera unit was allowed to reach thermal stabilization in a controlled-temperature lab before each measurement session. Both the integration time, and temperature range intervals were chosen to represent typical field deployment conditions. The average dark current signal showed a clear linear dependence with integration time, for a constant environmental temperature setting. The slope of this linear relation increased with the ambient temperature, whereas the intercept was insensitive to temperature changes. The standard deviation of the dark current signal was a function of integration time, but independent of the ambient temperature setting. These results allowed modeling the dark current signal as a function of the integration time and the camera body temperature. To minimize the dark current for a given integration time setting, measurements should be performed under the coldest possible conditions, in opposition to manufacturer recommendations. As a direct consequence of these results, the useful dynamic range for science applications with this MCT camera is reduced with increasing integration times and ambient temperatures. For instance, when acquiring images with 5 ms integration time, at 22°C ambient temperature, the resulting dark current signal reduces the maximum useful dynamic range in about 20%. The results shown here can be promptly adapted to other applications with MCT cameras, especially in situations with a non-controlled thermal environment, or when analyzing the reflective properties of cold targets.

Sensitive detection of cancer cells using light-mediated apta-PCR.

Apta-PCR is an ultrasensitive assay in which aptamers are exploited not only as biomolecular recognition elements, but also as reporter labels for amplification via real-time PCR. This methodology has been successfully applied to the detection of proteins, achieving limits of detection in the picomolar range. The introduction of caged aptamers that bear photo-labile groups, so called cages, at strategic positions so that their tertiary structure and thus their binding properties can be controlled by light, facilitates a more robust and attractive assay in terms of sample conservation and reusability. In this work, we report for the first time the use of caged aptamers for cell detection in an apta-PCR assay. Specifically, a sandwich format is used combining the capture of B-cells by an antibody with the specific detection of Burkitt's lymphoma cancer cells by a caged aptamer, acting as a reporter probe. Elution of the aptamer bound to the cancer cells is performed by light and the number of cells is then correlated with the amount of eluted caged aptamer using real-time PCR analysis. The reported technique shows an excellent sensitivity, achieving detection of as few as 77 cells, and due to the inherent robustness of the assay, this detection platform can be reused for further analyses, demonstrating potential applicability in proteomics and clinical diagnostics.

Selective uncaging of DNA through reaction rate selectivity.

The synthesis and use of the new nucleobase-caged nucleotides dT(pHP) and dT(NDEACM) is reported. Through a combination of time and wavelength selectivity four levels of selective uncaging with only two cages, and only two wavelengths, were obtained. The new residue dT(pHP) can be uncaged at 313 nm without the formation of unwanted cyclic pyridine dimers.

Wavelength-selective uncaging of oligonucleotides.

Caged compounds are light-sensitive molecules with temporarily inactivated biological function. The active compound is released upon irradiation, in which exact spatial and temporal control is accomplished. Beyond this inherently irreversible concept of triggering, the idea of multi-wavelength uncaging provides experiments with more complexity. This unit describes the syntheses of protected nucleoside phosphoramidites of caged dT(NpHP) [pHP = (p-hydroxyphenacyl)], dT(DEACM) {DEACM = [(7-diethylaminocoumarin-4-yl)methyl]} or a dC(NDBF) {NDBF = [1-(3-nitrodibenzofuran-1-yl)ethyl]} modification on the nucleobase, their incorporation in oligonucleotides, characterization, and their wavelength-selective uncaging up to four levels.

Four levels of wavelength-selective uncaging for oligonucleotides.

In this study the new nucleobase-caged nucleotides dT(NpHP) and dT(DEACM) are introduced. Together with two other caging groups (NDBF and NPP) this results in four layers of wavelength-selective uncaging for oligonucleotides, sequentially going from 505 to 440 nm, 365 nm, and finally to 313 nm for the photolysis reaction.

[Frontal mass: diagnostic challenges]. / Tumefacção frontal: desafios de diagnóstico.

Capnocytophaga spp. are part of the oral flora of humans and animals, being responsible for skin and soft tissues infections and invasive infections. Microbiological identification can be difficult due to its slow growth. We present a case of infection caused by this bacteria in the form of an extracerebral intracranial abscess, presenting as a frontal mass that posed some diagnostic challenges. A surgical drainage was performed together with antibiotic therapy with favourable outcome. This microorganism was identified in the second week of treatment and then a careful history revealed a dog bite days prior to the initial symptoms. This could have been the site of entry to a posterior focalization.

Functional detection of proteins by caged aptamers.

While many diagnostic assay platforms enable the measurement of analytes with high sensitivity, most of them result in a disruption of the analyte's native structure and, thus, in loss of function. Consequently, the analyte can be used neither for further analytical assessment nor functional analysis. Herein we report the use of caged aptamers as templates during apta-PCR analysis of targets. Aptamers are short nucleic acids that fold into a well-defined three-dimensional structure in which they interact with target molecules with high affinity and specificity. Nucleic acid aptamers can also serve as templates for qPCR approaches and, thus, have been used as high affinity ligands to bind to target molecules and subsequently for quantification by qPCR, an assay format coined apta-PCR. Caged aptamers in turn refer to variants that bear one or more photolabile groups at strategic positions. The activity of caged aptamers can thus be turned on or off by light irradiation. The latter allows the mild elution of target-bound aptamers while the target's native structure and function remain intact. We demonstrate that this approach allows the quantitative and subsequently the functional assessment of analytes. Since caged aptamers can be generated emanating from virtually every available aptamer, the described approach can be generalized and adopted to any target-aptamer pair and, thus, have a broad applicability in proteomics and clinical diagnostics.

[Post-traumatic meningitis in children: eleven years' analysis]. / Meningite bacteriana pós-traumática em idade pediátrica: análise de onze anos.

INTRODUCTION: Traumatic brain injury is a frequent reason for admission at pediatric emergency services. In severe cases, with basilar skull fracture, bacterial meningitis is a serious and potentially fatal complication to be considered. OBJECTIVE: To describe clinical and laboratory features, bacteriology and outcome of children with post-traumatic meningitis, and evaluate the proportion of meningitis in the population who suffered head trauma. METHODS AND MATERIALS: Retrospective review of medical records of children with this diagnosis admitted to a level 3 pediatric hospitals in the Central Region of Portugal, contextualized in the evaluation of the number of head injuries, fractures and cerebrospinal fluid leakages, during a 11-year period (January 1999 to December 2009). RESULTS: Four children were identified, corresponding to 0,7% of the children with skull fractures, 4,1% of children with basilar skull fractures and 13,8% of those with documented cerebrospinal fluid leakage. Three were boys, with a median age of 8 years (2-10 years). The median time between head trauma and meningitis was 1,1 years (3 days-3,4 years). In all cases a basilar skull fracture was identified and cerebrospinal fluid leakage documented. Two children required surgery. Streptococcus pneumonia was the pathogen identified in two cases with positive cerebrospinal fluid culture. One child died and other has post-traumatic peripheral facial palsy. CONCLUSIONS: Bacterial meningitis is a complication to be considered in head injury with basilar skull fracture, particularly when associated with cerebrospinal fluid leakage, even though the injury occurred several years earlier, and is usually a serious condition. One of our children died. Similar to what is described, S. pneumoniae was the most common bacteria, and this fact supports that children with head trauma and cerebrospinal fluid leakage should receive pneumococcal vaccine. The follow-up of these children requires constant vigilance and should include a multidisciplinary approach.

Comparison of the duplex-destabilizing effects of nucleobase-caged oligonucleotides.

Nucleobase-caged oligonucleotide residues have photolabile "caging groups" that prevent the formation of Watson-Crick base pairs until the unmodified nucleobase is restored in a photolysis event. This principle can be used to put a growing variety of powerful nucleic acid-based applications under the precise spatiotemporal control using light as an addressing mechanism. Examples for applications include light control of transcription, RNAi, nucleic acid folding, primer extension, and restriction endonuclease as well as DNAzyme, aptamer, and antisense activity. However, a comparison of the duplex-destabilization properties of the various caged residues that have been used up to date and rules for achieving a maximal duplex destabilization with a minimum amount of modified residues are still missing. We present both a comparison of the duplex-destabilizing capabilities of various nucleobase-caged residues and address the question of influence on neighboring base pairs.

[Recurrent bacterial meningitis]. / Meningite bacteriana recorrente.

BACKGROUND: Recurrent bacterial meningitis (RBM) is an unusual entity and usually poses a considerable diagnostic challenge. Different conditions can predispose for recurrence of episodes and the isolated pathogen can guide the diagnosis. The aim of this study was to characterize all RBM admitted to our tertiary paediatric hospital. METHODS: Retrospective analysis of the medical records of all children with RBM, between January 1994 and December 2007 (14 years). RESULTS: During this period, 107 children with bacterial meningitis (BM) were admitted. Among those, 10 (9.3%) had more than 1 episode of BM. Five (4.7%) had cerebrospinal fluid shunt. In the other 5 (4.3%), 11 episodes of BM were identified. S. pneumoniae was isolated in the majority of episodes (4) followed by N. meningitis (2). An anatomical defect, namely post-traumatic CSF leakage, was present in 3 children and S. pneumoniae was isolated in all. A predisposing condition has not yet been identified in 2 children and no anatomical defect or immunodeficiency was found despite full investigation. CONCLUSIONS: It was identified a high proportion of RBM compared to other series, that could be explained by the fact of being a tertiary hospital. An anatomical defect was the most frequent cause and S. pneumoniae the most frequent bacteria. In cases without an obvious predisposing condition an exhaustive evaluation, including search for anatomical and immunological defects, was performed but no changes were identified.

An extrasolar planetary system with three Neptune-mass planets.

Over the past two years, the search for low-mass extrasolar planets has led to the detection of seven so-called 'hot Neptunes' or 'super-Earths' around Sun-like stars. These planets have masses 5-20 times larger than the Earth and are mainly found on close-in orbits with periods of 2-15 days. Here we report a system of three Neptune-mass planets with periods of 8.67, 31.6 and 197 days, orbiting the nearby star HD 69830. This star was already known to show an infrared excess possibly caused by an asteroid belt within 1 au (the Sun-Earth distance). Simulations show that the system is in a dynamically stable configuration. Theoretical calculations favour a mainly rocky composition for both inner planets, while the outer planet probably has a significant gaseous envelope surrounding its rocky/icy core; the outer planet orbits within the habitable zone of this star.

Mercury's capture into the 3/2 spin-orbit resonance as a result of its chaotic dynamics.

Mercury is locked into a 3/2 spin-orbit resonance where it rotates three times on its axis for every two orbits around the sun. The stability of this equilibrium state is well established, but our understanding of how this state initially arose remains unsatisfactory. Unless one uses an unrealistic tidal model with constant torques (which cannot account for the observed damping of the libration of the planet) the computed probability of capture into 3/2 resonance is very low (about 7 per cent). This led to the proposal that core-mantle friction may have increased the capture probability, but such a process requires very specific values of the core viscosity. Here we show that the chaotic evolution of Mercury's orbit can drive its eccentricity beyond 0.325 during the planet's history, which very efficiently leads to its capture into the 3/2 resonance. In our numerical integrations of 1,000 orbits of Mercury over 4 Gyr, capture into the 3/2 spin-orbit resonant state was the most probable final outcome of the planet's evolution, occurring 55.4 per cent of the time.