Role of executive functions in the relations of state- and trait-math anxiety with math performance

The detrimental effect of math anxiety on math performance is thought to be mediated by executive functions. Previous studies have primarily focused on trait-math anxiety rather than state-math anxiety and have typically examined a single executive function rather than comprehensively evaluating all of them. Here, we used a structural equation modeling approach to concurrently determine the potential mediating roles of different executive functions (i.e., inhibition, switching, and updating) in the relationships between both state- and trait-math anxiety and math performance. A battery of computer-based tasks and questionnaires were administered to 205 university students. Two relevant results emerged. First, confirmatory factor analysis suggests that math anxiety encompassed both trait and state dimensions and, although they share substantial variance, trait-math anxiety predicted math performance over and above state-math anxiety. Second, working memory updating was the only executive function that mediated the relationship between math anxiety and math performance; neither inhibition nor switching played mediating roles. This calls into question whether some general proposals about the relationship between anxiety and executive functions can be extended specifically to math anxiety. We also raise the possibility that working memory updating or general cognitive difficulties might precede individual differences in math anxiety.

Emotional processing of math-related words in people with math anxiety

BACKGROUND

Research exploring emotional responses to math-related words in individuals with math anxiety (MA) is scarce. Here, we examined MA participants' subjective emotional processing of math-related cues within Lang's bioinformational model of emotion to further understand the role of those cues in MA.

METHODS

In total, 41 high-MA and 32 low-MA undergraduates rated math-related words, along with neutral, pleasant, and unpleasant words, from the Affective Norms for English Words. The Self-Assessment Manikin was used to calculate valence, arousal, and dominance scores for each word.

RESULTS

The low-MA group rated math-related words as neutral on the three emotional scales, however, the high-MA group rated them lower and higher for valence and dominance than neutral and unpleasant words, respectively. Moreover, math-related words were rated as more and less activating than neutral and unpleasant words, respectively. The two groups significantly differed in scores on the three scales only for the math-related words.

CONCLUSIONS

These results provide evidence that individuals with high MA show altered emotional processing of math-related words, experiencing them as moderately aversive and moderately activating. The findings emphasize that the altered emotional processing of words associated with math should be considered a symptom of MA.

The relationship between working memory updating components and reading comprehension

The objective of this study was to determine the contribution of retrieval and substitution components of working memory updating to reading comprehension. Difficulties in reading comprehension have been related to the inability to update information in working memory. Updating is a complex process comprising various subprocesses, such as retrieving information into the focus of attention and substituting information that is no longer relevant. Various numerical subtasks requiring or not requiring the substitution and retrieval components of working memory updating, as well as reading comprehension and general cognitive measures, were administered to a sample (n = 148) of 4th grade children. Less-skilled comprehenders showed lower accuracy when information retrieval was required. In contrast, substitution was not related to reading comprehension. These findings suggest that reading comprehension difficulties are related to the efficacy of information retrieval during updating in working memory.

Recollection contributes to children's reading comprehension: Using the process dissociation procedure in a working memory updating task

Recollection, rather than familiarity, seems to play a crucial part in sustaining children's reading comprehension. However, the roles of recollection and familiarity in both word reading and reading comprehension have yet to be fully understood. In this study, we examined estimates of recollection and familiarity in a working memory updating task using an adaptation of the process dissociation procedure. Our study involved 204 children aged 9-11 years. We administered a keeping track task in which lists of words belonging to various semantic categories (e.g., animals) were presented. The children had to follow two sets of instructions: (a) inclusion, which involved saying whether they had seen a word during the previous learning phase, and b) exclusion, which involved saying whether a word was the last one they had seen that belonged to a given category. Our results showed that recollection contributed to explain reading comprehension, but not word reading, performance. Familiarity, instead, did not predict either of the reading measures (word reading or reading comprehension). We discuss these findings in terms of the importance of considering recollection when studying reading processes during development. Alternative explanations considering the role of WM executive functioning are also considered.

Social network addiction symptoms and body dissatisfaction in young women: exploring the mediating role of awareness of appearance pressure and internalization of the thin ideal

BACKGROUND

Previous studies testing for a direct relationship between social networking sites (SNS) addiction and body dissatisfaction (BD) have yielded inconsistent results. Here, we aimed to identify underlying processes that could mediate this relationship. Specifically, we studied the relationship between SNS addiction symptoms and BD through the awareness of appearance pressures and the internalization of beauty ideals, both individually and serially: SNS addiction → Awareness → BD; SNS addiction → Internalization → BD; SNS addiction → Awareness → Internalization → BD.

METHOD

A total of 368 female undergraduates with SNS accounts completed scales to assess SNS addiction symptoms (Social Network Addiction Questionnaire), BD (Body Shape Questionnaire), awareness, and internalization (Sociocultural Attitudes Towards Appearance Questionnaire-4; awareness and internalization scales). A theoretical serial mediation model was constructed to examine the proposed relationships. Body mass index was included as a covariate to control the influence of this important variable.

RESULTS

The results indicated that both awareness and internalization independently mediated the relationship between SNS addiction symptoms and BD. Also, there was a significant serial mediation effect; women with more SNS addiction symptoms tended to be more aware of appearance pressure, which was associated with the internalization of beauty ideals. In turn, this internalization was positively related to BD symptoms.

CONCLUSIONS

These findings shed light on the indirect relationship between SNS addiction and BD, demonstrating independent and accumulative mediating effects of awareness and internalization.

Influence of the speed of deflation of the stent delivery system in the myocardial blush and ST-segment resolution in primary angioplasty: a randomized study

Introduction

Distal embolization may compromise the results of primary angioplasty. Our aim is to analyze the influence of the speed of deflation of the stent delivery system on the myocardial blush ≥2 and on the ST-Segment resolution ≥70%.

Methods

From December 2016 to February 2019, all consecutive patients with ST-elevation myocardial infarction who underwent urgent coronary angiography at our institution who were susceptible of thrombectomy, IIB-IIIA inhibitors and direct stenting were randomized 1:1 to fast deflation of the stent delivery system (group 1, n=103) or to slow deflation at 1 atm/second (group 2, n=107). Pre- and postdilatation was not allowed per protocol. The primary outcomes were the myocardial blush ≥2 and the ST-Segment resolution ≥70% while the size of myocardial damage, ejection fraction at discharge and at 12 months and total and cardiovascular mortality at 12 months were the secondary outcomes. A multivariate analysis was performed to analyze the influence of the speed of deflation of the stent delivery system in both primary end-points in case of possible imbalances among groups despite the randomization.

Results

Both groups represented 47% of the 447 procedures of primary angioplasty performed in that period. Baseline characteristics of the whole cohort: female gender 46 (21.9%), age 59.5±10.6 years, diabetes 35 (16.7%), Killip class IV 5 (2.4%), total ischemic time 177.5 (124–275) minutes and door to balloon time 84 (66–120.5) minutes. There were not differences in clinical or angiographic characteristics between both groups, although there was a non-significant trend towards larger reference vessel diameter in the slow deflation group (2.74±0.42 vs. 2.86±0.47, p=0.07). The study was prematurely stopped with 50% of the calculated sample size due to futility. The primary endpoint of myocardial blush ≥2 occurred in 77 (74.7%) vs. 79 (75.2%), p=0.93 and ST-Segment resolution ≥70% in 54 (53.9%) vs. 59 (55.5%), p=0.75 in group 1 and 2, respectively, without differences in any of the secondary endpoints. The speed of deflation of the stent delivery system did not show any influence on the MB or ST-Segment resolution ≥70% in the multivariate analysis. Predictors of myocardial blush ≥2 were systolic blood pressure at admission, creatinine clearance <60 ml/min and maximal diameter postprocedure. Diabetes, previous infarction, left anterior descending, TIMI ≥2 before intervention, TIMI 3 after intervention and collateral supply grade ≥2 were predictors of ST segment resolution≥70% with an area under the curve of 0.71 (0.63–0.80) and 0.75 (0.68–0.82), respectively.

Conclusions

In our series, the speed of deflation of the stent delivery system in primary angioplasty did not modified the myocardial blush ≥2 or ST-Segment resolution ≥70% and neither showed any influence in clinical outcomes, size of myocardial infarction by biomarkers and ejection fraction.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Abbott Laboratories

Cyber-dating abuse in young adult couples: Relations with sexist attitudes and violence justification, smartphone usage and impulsivity

Technologies have become important for interaction in couples. However, in some cases, controlling and aggressive behaviors can occur in the context of virtual interactions in couples; this is known as cyber-dating abuse (CDA). Identifying factors linked to CDA, as perpetrator and victim, are relevant for its prevention; therefore, more research is needed in this novel field of study. To contribute to the literature, our first goal was to analyze the associations among certain risk factors for CDA perpetration and victimization of, i.e., sexist attitudes and violence justification, problematic smartphone usage and impulsivity; sex and age were also considered. The second goal was to study whether there were differences in direct aggression and control, from the perpetrator and victim perspectives, with consideration of the above-mentioned risk factors. Third, differences in the diverse range of control behaviors and direct aggression between women and men were explored. To this end, 697 young adults (aged between 18 and 35 years; 548 women) completed self-report questionnaires that allowed assessment of the above-mentioned variables. The results showed that, among the wide range of CDA behaviors, indirect ones such as control behaviors were the most common. The highest level of control was strongly associated with the inability to manage behaviors under certain emotional states, especially negative ones, along with problematic smartphone usage. Sex differences were also observed: men displayed more sexist attitudes and violence justification, and perceived that they were more controlled by their partners. Regarding CDA behaviors, men and women showed differences in control (e.g. men considered themselves to be more controlled in terms of location and status updates), and direct aggression (e.g. men used more insults and humiliations than women). The results were discussed in terms of the importance of better understanding these risk factors to attenuate the increasing prevalence of CDA in relationships.

Recent results for the one-proton transfer reaction in the 18O+48Ti collision at 275 MeV

The 18O+48Ti reaction was studied at the energy of 275 MeV for the first time under the NUMEN and NURE experimental campaigns with the aim to investigate the complete net of reaction channels potentially involved in the 48Ca→48Ti double charge exchange transition. Such a transition is of great interest because of its relevance to the extraction of 48Ca→48Ti double beta decay nuclear matrix element. The relevant experiment was carried out at the MAGNEX facility of INFN-LNS in Catania. Angular distribution measurements for the various reaction products were performed by using the MAGNEX large acceptance magnetic spectrometer. The present contribution is focused on the analysis of the one-proton transfer channel with emphasis on the particle identification technique and the estimation of background contaminations.

Age-related changes in selection, recognition, updating and maintenance information in WM. An ERP study in children and adolescents

Possible age-related changes in different working memory (WM) subcomponents were assessed by analyzing the event-related-potentials associated with the n-back task. Two versions of the task (0- and 1-back) were administered to 168 subjects between 6 and 20 years of age. In both n-back tasks, lists of symbol-letter pairs were presented. Participants had to select the letter and decide whether it matched the target in memory. Selection-matching of the relevant item, as indexed by an N2pc component, was evident in all age groups, indicating early maturation of this ability. The decreasing amplitude of the P300 with age, coupled with the longer duration of the load effect in young children, suggests that WM updating requires greater processing resources at younger ages. The slow wave, present during the maintenance period, showed an inversion of polarity with age in anterior sites that could reflect age-related changes in the active maintenance of information in WM.

10-MV SBRT FFF IRRADIATION TECHNIQUE IS ASSOCIATED TO THE LOWEST PERIPHERAL DOSE: THE OUTCOME OF 142 TREATMENT PLANS FOR THE 10 MOST COMMON TUMOUR LOCATIONS

There is a growing interest in the combined use of Stereotactic Body Radiation Therapy (SBRT) with Flattening Filter Free (FFF) due to the high local control rates and reduced treatment times, compared to conventionally fractionated treatments. It has been suggested that they may also provide a better radiation protection to radiotherapy patients as a consequence of the expected decrease in peripheral doses. This work aims to determine this reduction in unattended out-of-field regions, where no CT information is available but an important percentage of second primary cancers occur. For that purpose, ten different cases suitable for SBRT were chosen. Thus, 142 different treatment plans including SBRT, as well as 3D-CRT, IMRT and VMAT (with standard fractionation) in low and high energies for Varian (FF and FFF), Siemens and Elekta machines were created. Then, photon and neutron peripheral dose in 14 organs were assessed and compared using two analytical models. For the prostate case, uncomplicated and cancer free control probability estimation was also carried out. As a general behavior, SBRT plans led to the lowest peripheral doses followed by 3D-CRT, VMAT and IMRT, in this order. Unflattened beams proved to be the most effective in reducing peripheral doses, especially for 10 MV. The obtained results suggest that FFF beams for SBRT with 10 MV represent the best compromise between dose delivery efficiency and peripheral dose reduction.

Optical communications downlink from a low-earth orbiting 1.5U CubeSat

In this article, we present the first demonstration of an optical communications downlink from a low-earth orbiting free-flying CubeSat. Two 1.5U vehicles, AC7-B&C, built under NASA's Optical Communications and Sensors Demonstration (OCSD) program were launched in November 2017 and subsequently placed into a 450-km, 51.6° inc. circular orbit. Pseudorandom data streams using on-off key (OOK) modulation were transmitted from AC-7B to a 40 cm aperture telescope located at sea level in El Segundo, CA. At 200 Mbps, without forward error correction (FEC), we achieved a 115-second link that was ~78% error free, with the remaining portion exhibiting an error rate below 1E-5. At the time of the engagement, the 1064-nm laser transmitter was operating at 2 W (half capacity) with a full width half maximum (FWHM) beam divergence of ~1 mrad, which was approximately double the anticipated pointing accuracy of the vehicle.

Nearest transfer effects of working memory training: A comparison of two programs focused on working memory updating

This study analyzed the mechanisms involved in possible transfer effects for two different working memory updating (WMU) training programs administered to young adults and based on two updating paradigms: n-back and arithmetical updating. The influence of practice distribution on transfer effects was also explored by including two training regimens: massed and spaced practice. Performance on different WMU tasks more or less structurally similar to the tasks used in the training was assessed to analyze the nearest transfer effects. Near and far transfer effects were tested using complex working memory (WM) and fluid intelligence tasks. The results showed that the WMU training produced gains in only some of the WMU tasks structurally similar to those used in the training, not in those lacking the same structure, or in WM or fluid intelligence tasks. These limited nearest transfer effects suggest that gains could be due to the acquisition of a specific strategy appropriate for the task during the training rather than to any improvement in the updating process per se. Performance did not differ depending on the training regimen.

The nuclear matrix elements of 0νββ decay and the NUMEN project at INFN-LNS

The goal of NUMEN project is to access experimentally driven information on Nuclear Matrix Elements (NME) involved in the neutrinoless double beta decay (0νββ), by high-accuracy measurements of the cross sections of Heavy Ion (HI) induced Double Charge Exchange (DCE) reactions. The knowledge of the nuclear matrix elements is crucial to infer the neutrino average masses from the possible measurement of the half-life of 00νββ decay and to compare experiments on different isotopes. In particular, the (18O, 18Ne) and (20Ne, 20O) reactions are performed as tools for β+β+ and β-β- decays, respectively. The experiments are performed at INFN - Laboratory Nazionali del Sud (LNS) in Catania using the Superconducting Cyclotron (CS) to accelerate the beams and the MAGNEX magnetic spectrometer to detect the reaction products. The measured cross sections are very low, limiting the present exploration to few selected isotopes of interest in the context of typically low-yield experimental runs. In order to make feasible a systematic study of all the candidate nuclei, a major upgrade of the LNS facility is foreseen to increase the experimental yield of about two orders of magnitude. To this purpose, frontier technologies are going to be developed for both the accelerator and the detection systems. In parallel, advanced theoretical models will be developed to extract the nuclear structure information from the measured cross sections.

Characterization of radon levels in soil and groundwater in the North Maladeta Fault area (Central Pyrenees) and their effects on indoor radon concentration in a thermal spa

Radon levels in the soil and groundwater in the North Maladeta Fault area (located in the Aran Valley sector, Central Pyrenees) are analysed from both geological and radiation protection perspectives. This area is characterized by the presence of two important normal faults: the North Maladeta fault (NMF) and the Tredós Fault (TF). Two primary aspects make this study interesting: (i) the NMF shows geomorphic evidence of neotectonic activity and (ii) the presence of a thermal spa, Banhs de Tredós, which exploits one of the several natural springs of the area and needs to be evaluated for radiation dosing from radon according to the European regulation on basic safety standards for protection against ionizing radiation. The average soil radon and thoron concentrations along a profile perpendicular to the two normal faults - 22 ± 3 kBq·m^-3 and 34 ± 3 kBq·m^-3, respectively - are not high and can be compared to the radionuclide content of the granitic rocks of the area, 25 ± 4 Bq·kg^-1 for ²²⁶Ra and 38 ± 2 Bq·kg^-1 for ²²⁴Ra. However, the hypothesis that the normal faults are still active is supported by the presence of anomalies in both the soil radon and thoron levels that are unlikely to be of local origin together with the presence of similar anomalies in CO₂ fluxes and the fact that the highest groundwater radon values are located close to the normal faults. Additionally, groundwater ²²²Rn data have complemented the hydrochemistry data, enabling researchers to better distinguish between water pathways in the granitic and non-granitic aquifers. Indoor radon levels in the spa vary within a wide range, [7-1664] Bq·m^-3 because the groundwater used in the treatment rooms is the primary source of radon in the air. Tap water radon levels inside the spa present an average value of 50 ± 8 kBq·m^-3, which does not exceed the level stipulated by the Spanish Nuclear Safety Council (CSN) of 100 kBq·m^-3 for water used for human consumption. This finding implies that even relatively low radon concentration values in water can constitute a relevant indoor radon source when the transfer from water to indoor air is efficient. The estimated effective dose range of values for a spa worker due to radon inhalation is [1-9] mSv·y^-1. The use of annual averaged radon concentration values may significantly underestimate the dose in these situations; therefore, a detailed dynamic study must be performed by considering the time that the workers spend in the spa.

Focus Switching in Working Memory

Abstract. Focus switching in working memory involves accessing an object in the focus of attention in order to retrieve its content. Objects in working memory can be viewed as consisting of two types of information: contents (e.g., numerical information) and contexts (e.g., cues to retrieve the contents). This study examined the extent to which content retrieval and context access may be separated. Three experiments were carried out in which object switching and content retrieval were manipulated. In addition, the alternation between the retrieval operations was also manipulated. The main result was that content retrieval required time over and above that needed to access the object. This finding supports the idea that contexts and their contents may be accessed independently when an object is brought into the focus.

Age-related differences in working memory updating components

The aim of this study was to investigate possible age-related changes throughout childhood and adolescence in different component processes of working memory updating (WMU): retrieval, transformation, and substitution. A set of numerical WMU tasks was administered to four age groups (8-, 11-, 14-, and 21-year-olds). To isolate the effect of each of the WMU components, participants performed different versions of a task that included different combinations of the WMU components. The results showed an expected overall decrease in response times and an increase in accuracy performance with age. Most important, specific age-related changes in the retrieval component were found, demonstrating that the effect of retrieval on accuracy was larger in children than in adolescents or young adults. These findings indicate that the availability of representations from outside the focus of attention may change with age. Thus, the retrieval component of updating could contribute to the age-related changes observed in the performance of many updating tasks.

Soil radon dynamics in the Amer fault zone: An example of very high seasonal variations

Soil radon levels of the Amer fault zone have been measured for a 4 year-period with the aim of checking seasonal fluctuations obtained in previous studies and to understand radon origin and dynamics. In this manuscript additional results are presented: updated continuous and integrated soil radon measurements, radionuclide content of soil materials and a detailed analysis of an urban profile by means of the electrical resistivity imaging technique and punctual soil radon, thoron and CO2 measurements. Integrated and continuous measurements present a wide range of values, [0.2-151.6] kBq m(-3) for radon, [4.5-39.6] kBq m(-3) for thoron and [4.0-71.2] g m(-2) day(-1) for CO2. The highest soil radon levels in the vicinity of the Amer fault (>40 kBq m(-3)) are found close to the fractured areas and present very important fluctuations repeated every year, with values in summer much higher than in winter, confirming previous studies. The highest radon values, up to 150 kBq m(-3), do not have a local origin because the mean value of radium concentration in this soil (19 ± 5 Bq kg(-1)) could not explain these values. Then soil radon migration through the fractures, influenced by atmospheric parameters, is assumed to account for such a high seasonal fluctuation. As main conclusion, in fractured areas, seasonal variations of soil radon concentration can be very important even in places where average soil radon concentration and radium content are not especially high. In these cases the migration capability of the soil is given not by intrinsic permeability but by the fracture structure. Potential risk estimation based on soil radon concentration and intrinsic permeability must be complemented with geological information in fractured systems.

A simple flow cytometry method improves the detection of phosphatidylserine-exposing extracellular vesicles

BACKGROUND

Plasma contains cell-derived extracellular vesicles (EVs), which participate in physiopathological processes and have potential applications as disease biomarker. However, the enumeration of EVs faces major problems, due to their sub-micrometer size and to intrinsic limitations in methods of characterization, mainly flow cytometry (FCM).

OBJECTIVES

Our objective is to enumerate EVs in plasma, by taking as the prototype the population of phosphatidylserine (PS)-exposing EVs, which constitute one of the major EV populations and are responsible for thrombotic disorders.

METHODS

The concentration of PS-exposing EVs in platelet-free plasma (PFP) of healthy subjects was measured by FCM using either light scattering or fluorescence as the trigger and fluorescent Annexin-5 (Anx5) as the specific label. In addition, PS-exposing EVs were enumerated by electron microscopy (EM) after labeling with Anx5 gold nanoparticles and sedimentation on EM grids.

RESULTS

We show that about 50× more Anx5-positive EVs are detected by FCM when detection is triggered on fluorescence as compared with light scattering. By fluorescence triggering, concentrations of 22 000-30 000 Anx5-positive EVs per μL PFP were determined, using two different flow cytometers. The limit of detection of the fluorescence triggering method was estimated at about 1000-2500 Anx5 molecules. Results from EM suggest that EVs down to 100-150 nm diameter are detected by fluorescence triggering.

CONCLUSION

This study presents a simple method for enumerating EVs. We believe that this method is applicable in a general context and will improve our understanding of the roles of EVs in pathophysiological situations, which will open avenues for the development of EV-based diagnosis assays.

MCTP system model based on linear programming optimization of apertures obtained from sequencing patient image data maps

PURPOSE

The authors present a hybrid direct multileaf collimator (MLC) aperture optimization model exclusively based on sequencing of patient imaging data to be implemented on a Monte Carlo treatment planning system (MC-TPS) to allow the explicit radiation transport simulation of advanced radiotherapy treatments with optimal results in efficient times for clinical practice.

METHODS

The planning system (called CARMEN) is a full MC-TPS, controlled through aMATLAB interface, which is based on the sequencing of a novel map, called "biophysical" map, which is generated from enhanced image data of patients to achieve a set of segments actually deliverable. In order to reduce the required computation time, the conventional fluence map has been replaced by the biophysical map which is sequenced to provide direct apertures that will later be weighted by means of an optimization algorithm based on linear programming. A ray-casting algorithm throughout the patient CT assembles information about the found structures, the mass thickness crossed, as well as PET values. Data are recorded to generate a biophysical map for each gantry angle. These maps are the input files for a home-made sequencer developed to take into account the interactions of photons and electrons with the MLC. For each linac (Axesse of Elekta and Primus of Siemens) and energy beam studied (6, 9, 12, 15 MeV and 6 MV), phase space files were simulated with the EGSnrc/BEAMnrc code. The dose calculation in patient was carried out with the BEAMDOSE code. This code is a modified version of EGSnrc/DOSXYZnrc able to calculate the beamlet dose in order to combine them with different weights during the optimization process.

RESULTS

Three complex radiotherapy treatments were selected to check the reliability of CARMEN in situations where the MC calculation can offer an added value: A head-and-neck case (Case I) with three targets delineated on PET/CT images and a demanding dose-escalation; a partial breast irradiation case (Case II) solved with photon and electron modulated beams (IMRT + MERT); and a prostatic bed case (Case III) with a pronounced concave-shaped PTV by using volumetric modulated arc therapy. In the three cases, the required target prescription doses and constraints on organs at risk were fulfilled in a short enough time to allow routine clinical implementation. The quality assurance protocol followed to check CARMEN system showed a high agreement with the experimental measurements.

CONCLUSIONS

A Monte Carlo treatment planning model exclusively based on maps performed from patient imaging data has been presented. The sequencing of these maps allows obtaining deliverable apertures which are weighted for modulation under a linear programming formulation. The model is able to solve complex radiotherapy treatments with high accuracy in an efficient computation time.

A system to measure isomeric state half-lives in the 10 ns to 10 μs range

The Isomeric State Measurement System (SISMEI) was developed to search for isomeric nuclear states produced by fusion-evaporation reactions. The SISMEI consists of 10 plastic phoswich telescopes, two lead shields, one NaI(Tl) scintillation detector, two Compton suppressed HPGe γ-ray detectors, and a cone with a recoil product catcher. The new system was tested at the 8 UD Pelletron tandem accelerator of the University of São Paulo with the measurement of two known isomeric states: (54)Fe, 10(+) state (E = 6527.1 (11) keV, T(1/2) = 364(7) ns) and the 5/2(+) state of (19)F (E = 197.143 (4) keV, T(1/2) = 89.3 (10) ns). The results indicate that the system is capable of identifying delayed transitions, of measuring isomeric state lifetimes, and of identifying the feeding transitions of the isomeric state through the delayed γ-γ coincidence method. The measured half-life for the 10(+) state was T(1/2) = 365(14) ns and for the 5/2(+) state, 100(36) ns.

Extracellular vesicles from blood plasma: determination of their morphology, size, phenotype and concentration

BACKGROUND

Plasma and other body fluids contain membranous extracellular vesicles (EVs), which are considered to derive from activated or apoptotic cells. EVs participate in physiological and pathological processes and have potential applications in diagnostics or therapeutics. Knowledge on EVs is, however, limited, mainly due to their sub-micrometer size and to intrinsic limitations in methods applied for their characterization.

OBJECTIVES

Our aim was to provide a comprehensive description of EVs from plasma of healthy subjects.

METHODS

Cryo-transmission electron microscopy combined with receptor-specific gold labeling was used to reveal the morphology, size and phenotype of EVs. An original approach based on sedimentation on electron microscopy grids was developed for enumerating EVs. A correlation was performed between conventional flow cytometry and electron microscopy results.

RESULTS

We show that platelet-free plasma samples contain spherical EVs, 30 nm to 1 μm in diameter, tubular EVs, 1-5 μm long, and membrane fragments, 1-8 μm large. We show that only a minority of EVs expose the procoagulant lipid phosphatidylserine, in contrast to the classical theory of EV formation. In addition, the concentrations of the main EV sub-populations are determined after sedimentation on EM grids. Finally, we show that conventional flow cytometry, the main method of EV characterization, detects only about 1% of them.

CONCLUSION

This study brings novel insights on EVs from normal plasma and provides a reference for further studies of EVs in disease situations.

[The pyramidal tract: new pathways]

OBJECTIVE

To review some anatomofunctional aspects of the pyramidal tract which are relevant in clinical practice, especially the newer concepts.

DEVELOPMENT

a) Although the motor function is best known, the pyramidal tract also has sensory functions, modulating the transmission of impulses in the spinal cord. In fact, motor function is a recent acquisition on the evolutionary scale. b) Other descending pathways, such as the cortico reticulospinal path, participate in voluntary movements. However, the pyramidal pathway is necessary for fine movements of the hand. c) Most of the pyramidal fibres control movements of the contralateral side of the body, but there are a few fibres which do not cross to the other side and play a part in ipsilateral body movements. These fibres seem to contribute to motor recovery following a brain lesion. d) Classically it is recognized that the motor cortex and pyramidal fibres follow a somatotopical distribution. Nevertheless territories corresponding to different parts of the body are superimposed to a considerable extent and may be modified on very diverse occasions. e) Experimentally it has been proved that a circumscribed lesion of the pyramidal pathway does not cause hyper reflexia or spasticity. The hyper reflexia and spasticity habitually seen in patients with pyramidal syndrome is due to lesions of other descending pathways.

CONCLUSION

The pyramidal tract is anatomically and functionally related to other nerve structures and its activity is therefore integrated within the nervous system.

[A radiological study of the cervical alterations in Down syndrome. New findings on computerized tomography and three dimensional reconstructions]

OBJECTIVE

We studied a large proportion of the population in our health district who have Down's syndrome to determine the incidence and variety of changes in the spine and to define the guidelines for preventive diagnosis advisable in relation to atlanto-axial instability, a common disorder in these patients.

PATIENTS AND METHODS

First phase: a plain X-ray of the cervical spine in a neutral lateral projection and in flexion in 188 patients, measuring the atlanto-odontoid distance. Second phase: computerized tomography (CT) studies and three dimensional reconstructions in 25 patients (13.3%) chosen at random. The axial cuts from the upper portion of C3 to the occiput were 3 mm in thickness with 3 mm intervals and a standard reconstruction algorithm.

RESULTS

The incidences of atlanto-axial instability with an atlodontoid distance (3)5 mm were not comparable with the published series. There was a lower incidence (4.2%), with no difference between measurements in flexion and in the neutral lateral views. There was a greater incidence of malformations than in other reports, including a rare case of os odontoideum and also constant asymmetry of the occipital condyles (100%) in the patients of the CT series and consequently instability of the atlas (96%) and off-centered odontoides (84%).

CONCLUSIONS

The study showed that there was deficient asymmetrical development of the occipital bone, which caused different heights of the occipital condyles and led to cervico-cranial mal-position. For study of the degree of error of position and congenital anomalies. We recommend replacing plain X-ray studies by CT with three dimensional reconstructions.

The glenolabral articular disruption lesion: MR arthrography with arthroscopic correlation

OBJECTIVE

The purpose of this study was to describe the MR arthrography appearance of the glenolabral articular disruption (GLAD) lesion. Proper diagnosis of this lesion is important because it can be a source of persistent shoulder pain that requires surgical repair and because it is often difficult to diagnose clinically.

MATERIALS AND METHODS

Findings on MR arthrography were retrospectively correlated with the clinical histories and physical examination findings of six patients in whom we saw the typical appearance of the GLAD lesion. Four of these patients underwent follow-up arthroscopy that included surgical proof of GLAD lesions.

RESULTS

Five of the six patients had a documented glenohumeral impaction injury associated with an abducted externally rotated shoulder. All six patients had persistent shoulder pain, but their shoulders were stable during routine examination. In all patients, MR arthrography showed a superficial tear of the anteroinferior labrum with an adjacent articular cartilage injury. The torn labrum remained firmly attached to the anterior scapular periosteum, and contrast material was seen to extend into the labral tear and cartilaginous defect.

CONCLUSION

The MR arthrography findings of GLAD lesions include a nondisplaced tear of the anteroinferior labrum with an adjacent chondral injury. The pattern of chondral injury can range from a cartilaginous flap tear to a depressed osteochondral injury of the articular cartilage and underlying bone.

Rheumatoid nodule of the foot: MRI appearances mimicking an indeterminate soft tissue mass

Subcutaneous rheumatoid nodules occur commonly in advanced cases of rheumatoid arthritis, but only rarely appear in the feet. We present a case of a subcutaneous rheumatoid nodule arising in the heel pad of a 68-year-old man with a long history of rheumatoid arthritis, along with a review of the literature. The appearance of the mass on MRI is illustrated and correlated with the histologic findings. The MRI appearance of a subcutaneous rheumatoid nodule is that of a nonspecific ill-defined mass with long T1- and long T2-relaxation times. A differential diagnosis for similar appearing masses is offered.

Recent advances in magnetic resonance imaging of the musculoskeletal system

Numerous recent technical innovations in magnetic resonance imaging have dramatically improved the imaging evaluation of musculoskeletal disease; however, with the introduction of new techniques comes the risk of inappropriate applications and unanticipated pitfalls in interpretation. Some of the practical and theoretical implications of these recent innovations as well as potential caveats associated with their use are highlighted in the following discussion.

[Deferred repair of surgical ureteral lesions]

Our experience in surgical injuries of the ureter, as well as the therapeutic approach followed to repair them as expounded in this paper. Immediate nephrostomy following diagnosis, and restoration deferred a minimum of three weeks have provided good results, as well as it has allowed us to detect and achieve spontaneous restoration in one case. These reasons, together with the absence of technical difficulties during the second intervention, invite us to consider the reevaluation and deferred restoration--if appropriate--of the surgical ureteral injuries as a therapeutic approach from which a number of patients can profit.

[Pubo-vaginal percutaneous suspension by the Gittes technique for stress incontinence. Initial experience]

The paper presents our initial experience with endoscopic suspension of the vesical neck, as per the modification introduced by Gittes and based on incorporation through the vaginal mucosa of non-absorbable single-filament sutures. In this way it is feasible to use a simple non-incisive vaginal surgery with minimum morbidity. Good results have been obtained so far in six of the seven patients operated on. No complications have presented following tube retrieval on the second day. It is our belief that these initial results can be a reasonable basis to a wider use of this technique and to know its long-term results in treating stress incontinency through urethral hypermobility.

[Incidental carcinoma of the kidney with renal vein thrombosis]

Incidental carcinoma of kidney is an increasingly common pathology as a result of a wider use of high resolution diagnostic methods. The special characteristics of these tumors, usually small and in a low grade or stage, make conservative surgery to be considered as a valid therapeutical option. An incidental carcinoma of kidney with tumoral thrombosis of the renal vein undetected in the pre-surgical study, circumstance which allows to emphasize the malignant potential of these tumors is presented here. Based on this, we believe that a meticulous evaluation of the renal vein condition should be made, in patients considered as possible candidates for conservative surgery. In this sense, selective renal phebography and magnetic resonance could be considered explorative means that play an important role in the introduction of renal preservation surgery, if future studies show that its use allows an early detection of the tumoral condition of renal vein.

Clinical trial of remote radiologist services for a military installation

It is often difficult to provide continuity of professional radiological services at U.S. military facilities located at a distance from major metropolitan areas. To address this problem, we have designed and evaluated a program to send x-ray films from a U.S. Army hospital to a remote site for expert radiological interpretation. Nine hundred and forty-two x-ray studies were sent by U.S. Express Mail from the Radiology Department of a U.S. Army Hospital over a 2-month period. The typed reports were sent back to the hospital through the use of a computer-to-computer telephone link within 72 hours of film transport. No studies were lost and security of all studies was maintained. This program offers a cost-effective, otherwise unavailable means to provide high quality professional radiological services to U.S. military facilities both inside the United States and in foreign countries.