Differences in kinetic characteristics during countermovement jump of football players with cerebral palsy according to impairment profiles

Objectives: The purpose of this study was 1) to determine and compare kinetic parameters during the realization of a countermovement jump (CMJ) between footballers with cerebral palsy (CP) and non-impaired footballers, and 2) to analyze the differences in this action between different players' impairment profiles and a group of non-impaired footballers. Methods: This study involved 154 participants comprising 121 male footballers with CP from 11 national teams and 33 male non-impaired football players recruited as the control group (CG). The footballers with CP were described according to the different impairment profiles (bilateral spasticity = 10; athetosis or ataxia = 16; unilateral spasticity = 77; minimum impairment = 18). All participants performed three CMJs on a force platform to record kinetic parameters during the test. Results: The group of para-footballers presented significantly lower values than the CG in the jump height (p < 0.01, d = -1.28), peak power (p < 0.01, d = -0.84), and the net concentric impulse (p < 0.01, d = -0.86). Concerning the pairwise comparisons between CP profiles and the CG, significant differences were found for the bilateral spasticity, athetosis or ataxia, and unilateral spasticity subgroups compared to the non-impaired players for jump height (p < 0.01; d = -1.31 to -2.61), power output (p < 0.05; d = -0.77 to -1.66), and concentric impulse of the CMJ (p < 0.01; d = -0.86 to -1.97). When comparing the minimum impairment subgroup with the CG, only significant differences were found for jump height (p = 0.036; d = -0.82). Footballers with minimum impairment presented higher jumping height (p = 0.002; d = -1.32) and concentric impulse (p = 0.029; d = -1.08) compared to those with bilateral spasticity. Also, the unilateral spasticity subgroup reports a higher jump height performance than the bilateral group (p = 0.012; d = -1.12). Conclusion: These results suggest that the variables related to power production during the concentric phase of the jump are crucial for the performance differences between groups with and without impairment. This study provides a more comprehensive understanding of kinetic variables that would differentiate CP and non-impaired footballers. However, more studies are necessary to clarify which parameters better differentiate among different profiles of CP. The findings could help to prescribe effective physical training programs and support the classifier's decision-making for class allocation in this para-sport.

What Is the Relationship between Trunk Control Function and Arm Coordination in Adults with Severe-to-Moderate Quadriplegic Cerebral Palsy?

Adults with tetraparesis cerebral palsy (i.e., wheelchair users) tend to experience more accelerated ageing, resulting in physical deterioration that increases the impact of the disability, leading to a loss of mobility that interferes with people's daily activities and participation in the community. The aim of this work is to study the relationship between trunk control and the function of the less-affected arm in this population. For this purpose, 41 para-athletes were invited to participate in this study, performing five tests to assess upper limb coordination, two tests to assess manual dexterity [i.e., Box and Block Test (BBT) and Box and Ball Test (BBLT)] and three tests to assess intra-limb coordination in different planes. Trunk control was assessed in both static and dynamic sitting conditions. The results show moderate correlations between static postural control and manual dexterity tests in the BBT (r = -0.553; p = 0.002) and BBLT (r = -0.537; p = 0.004). Large correlations were also found between static postural control and intra-limb tasks in horizontal (r = 0.769; p = 0.001) and vertical movements (r = 0.739; p = 0.009). Better static trunk control is related to a better upper limb function in the sagittal plane. Considerations and implications are explained in the manuscript.

Effect of acute exercise intensity on cognitive inhibition and well-being: Role of lactate and BDNF polymorphism in the dose-response relationship

Introduction

There is evidence in the literature that acute exercise can modify cognitive function after the effort. However, there is still some controversy concerning the most effective exercise modality to improve cognitive function in acute interventions. Regarding these different exercise modalities, the dose-response relationship between exercise intensity and cognitive response is one of the most challenging questions in exercise and cognition research.

Methods

In this study, we tested the impact of moderate-intensity (MICT), high-intensity (HIIT) exercise sessions, or control situation (CTRL) on cognitive inhibition (measured with the Stroop Test). Thirty-six young college students participated in this study, where a within-subject repeated measure design was used.

Results

ANOVA 2×3 demonstrated that HIIT improved the acute cognitive response to a higher degree when compared to MICT or CTRL (p < 0.05). The cognitive improvements correlated with lactate release, providing a plausible molecular explanation for the cognitive enhancement (r < -0.2 and p < 0.05 for all the Stroop conditions). Moreover, a positive trend in wellbeing was observed after both exercise protocols (HIIT and MICT) but not in the CTRL situation. Genetic BDNF single nucleotide polymorphism did not influence any interactions (p < 0.05).

Discussion

In this sense, our results suggest that exercise intensity could be a key factor in improved cognitive function following exercise in young college students, with no additional impact of BDNF polymorphism. Moreover, our results also provide evidence that exercise could be a useful tool in improving psychological wellbeing.

Memory Modulation by Exercise in Young Adults Is Related to Lactate and Not Affected by Sex or BDNF Polymorphism

Currently, high-intensity interval exercise (HIIE) is on the rise compared to moderate-intensity exercise (MIE) due to its similar benefits for health and performance with low time requirements. Recent studies show how physical exercise can also influence cognitive function, although the optimal dose and underlying mechanisms remain unknown. Therefore, in our study, we have compared the effects on visuospatial and declarative memory of different exercise intensities (HIIE vs. MIE), including possible implicated factors such as lactate released after each session and the Brain-Derived Neurotrophic Factor (BDNF) genotype. Thirty-six undergraduate students participated in this study. The HIIE session consisted of a 3 min warm-up, four 2 min sets at 90−95% of the maximal aerobic speed (MAS) with 2 min of passive recovery between sets, and a 3 min cooldown, and the MIE session implies the same total duration of continuous exercise at 60% of the MAS. Better improvements were found after HIIE than MIE on the backward condition of the visuospatial memory test (p = 0.014, ηp2 = 0.17) and the 48 h retention of the declarative memory test (p = 0.04; d = 0.34). No differences were observed in the forward condition of the visuospatial memory test and the 7-day retention of the declarative memory test (p > 0.05). Moreover, non-modifiable parameters such as biological sex and BDNF polymorphism (Val/Val, Val/Met, or Met/Met) did not modulate the cognitive response to exercise. Curiously, the correlational analysis showed associations (p < 0.05) between changes in memory (visuospatial and declarative) and lactate release. In this sense, our results suggest an important role for intensity in improving cognitive function with exercise, regardless of genetic factors such as biological sex or BDNF Val66Met polymorphism.

Different Exercise Types Produce the Same Acute Inhibitory Control Improvements When the Subjective Intensity Is Equal

Twenty-eight active older people (67.19 ± 4.91 years) who engaged in physical exercise activity twice a week were recruited to participate in a counterbalanced experimental protocol. The participants performed three different exercise sessions on three different days, one based on aerobic activities, one based on strength exercises with elastic bands, and one based on stationary balance games. During all three sessions, they were encouraged to maintain a moderate subjective intensity (5-6 on the RPE10 scale), and their heart rate was recorded. In addition, all of the participants took a digital version of the Stroop test before and after each session. The study aimed to compare the acute cognitive impacts of different types of exercise sessions in older adults. The participants' heart rate differed between the exercise sessions, but they maintained the RPE intensity. There was a significant improvement in inhibitory control (Stroop test) after all sessions, with no differences between exercise sessions. Moreover, some participants agreed to be genotyped to record the single nucleotide polymorphism of BDNF rs6265. There were no differences between Val/Val and Met carriers at the beginning or end of the exercise sessions. The present study showed similar cognitive improvements with different exercise type sessions when the subjective intensity was maintained.

To What Degree Does Limb Spasticity Affect Motor Performance in Para-Footballers With Cerebral Palsy?

Spasticity is considered a contributor to hypertonia, frequently presented in people with cerebral palsy (CP), affecting muscle function and motor activities. In CP football, the classification system determines that this impairment is eligible for competitive para-sports due to the impact on activity limitation and sports performance. However, the relationship between this feature (i.e., spastic hypertonia) and performance determinants has not been explored yet. This study aimed to assess the association of clinical spasticity measurements with the performance of sport-specific tests used for classification purposes. Sixty-nine international footballers with CP voluntarily participated in this study. The Australian Spasticity Assessment Scale was used to measure spasticity in lower limbs muscle groups and activity limitation tests were conducted considering dynamic balance, coordination, vertical and horizontal jumps, acceleration, and change of direction ability. Low-to-moderate negative significant associations were found between the hip spasticity and measures of dynamic balance and dominant unipedal horizontal jump capacity. Additionally, moderate associations were reported between the knee spasticity and the non-dominant unipedal horizontal jump capacity and the change of direction actions with the ball. The ankle spasticity score reported small to moderate associations with the change of direction assessment without the ball and bipedal and dominant unipedal horizontal jump capability. Finally, the total spasticity score only presented a significant association with horizontal jump performance. This is a novel study that provides evidence of the associations between an eligible neural impairment and relevant specific measures of activity limitation tests. These results suggest that the amount of spasticity according to each evaluated joint muscle group of the lower limbs presents a low-to-moderate significant relationship with determined measures of dynamic balance, coordination, horizontal jump, acceleration, and change of direction ability with and without the ball in international-level CP footballers. Further studies are necessary to elucidate the real contribution of neural and non-neural impairments related to hypertonia on fundamental sport-specific motor skills of para-footballers with CP.

Using Decision Trees to Support Classifiers' Decision-Making about Activity Limitation of Cerebral Palsy Footballers

This study aimed (1) to determine the appropriateness of using decision trees as a classification tool for determining the allocation of sport classes of para-footballers with "moderate vs. mild" cerebral palsy (CP) profiles of spastic diplegia/hemiplegia and ataxia/athetosis based on observational outcomes by international classifiers, and (2) to identify what key observational features were relevant to discriminating among different impairment levels. A sample of 16 experienced international classifiers from five world regions participated in this study, observing activity limitation of a final sample of 21 international CP footballers when performing 16 gross-motor and sports-specific tests for balance (n = 3), coordination (n = 5), running, accelerations and decelerations (n = 3), jumping (n = 4), and change of direction ability (n = 1). For the overall sample (336 observations), the model included eight decision nodes and 24 branches with 17 leaves, including side-step, side-stepping, and triple hop as the tests with the best sensitivity (precision = 67.0%). For those with spastic diplegia (64 observations: Two nodes, six branches with five leaves), the range of motion in the side-step test and the balance in the tandem walk tests correctly classified 89.1% of the observations. In those with athetosis and ataxia (96 observations), the model included five nodes, 15 branches, and 11 leaves (176 observations, precision = 86.5%). For those with spastic hemiplegia, a model containing two nodes, six branches, and five leaves had 90.9% accuracy, including observational features of balance in the side-step test and symmetry in the side-stepping test. The observational tool used in this study, based on the impact of specific impairment measurements of hypertonia, athetosis, and ataxia, can be used to determine which assessments are more appropriate for discriminating between functional profiles in para-footballers with CP.

Are Self-Efficacy Gains of University Students in Adapted Physical Activity Influenced by Online Teaching Derived From the COVID-19 Pandemic?

Due to the lockdown caused by the COVID-19 pandemic, e-learning suddenly spread to different levels of education, including university. In Spain, students of sports sciences are prepared during a 4-year study program to work in different areas (including physical education) and with different populations (including people with disabilities). The aims of this study were (1) to assess the effect of pandemic-driven online teaching on self-efficacy (SE) for the inclusion of people with disabilities in a group of university students enrolled in a compulsory course on adapted physical activity (APA); (2) compare the gains from SE before and after the APA course with a sample of students who followed the same course before the pandemic; and (3) explore the influence on SE scores according to three demographic variables: gender, previous SE training, and previous experience with people with disabilities. The study involved a sample of 124 university students (22.1 ± 2.6 years), distributed into two groups: prepandemic (n = 86) and pandemic (n = 38). They voluntarily completed the Spanish version of the Scale of Self-Efficacy of Physical Education Teachers of Physical Education toward Children with Disabilities, obtaining pre- and postcourse measurements. Due to the sudden lockdown, two-thirds of the pandemic course was taught online, and changes in the teaching strategies and tasks had to be made. Similar gains were obtained in both groups for the three subscales of the SE scale (p < 0.001, large effect sizes): intellectual, physical, and visual disability. No significant differences were found for comparisons between groups and the interaction effect of the course taught, nor for the three demographic co-variables. This study shows that teaching strategies that encourage student participation and reflections on learning increase student SE, regardless of the teaching format (i.e., face-to-face vs. online teaching). Moreover, the gains in SE are invariable to demographic co-variables.

Dynamic and static stability in para-athletes with cerebral palsy considering their impairment profile

BACKGROUND

Balance impairment is a common feature in people with cerebral palsy (CP), affecting the performance of daily-life and physical activities.

OBJECTIVES

To (1) explore the absolute and relative intrasession reliability of two balance tests to assess dynamic and static balance in ambulant para-athletes with CP; (2) explore the relationships between the two balance tests to determine potential application in sport classification; (3) assess the differences between CP profiles (ie, spastic diplegia, athetosis/ataxia, and spastic hemiplegia) in comparison to those with a minimum impairment; and (4) compare the outcomes of the static and dynamic balance of ambulant para-athletes with CP regarding controls.

METHODS

A group of 129 male well-trained para-footballers with CP, classified as Level I according to the Gross Motor Function Classification System, participated in the present study. Static balance was assessed using the One-Leg Stance test, performed bilaterally on a force platform, and the dynamic balance was assessed in two conditions of the Tandem Walk test (TW): walking heel-toe contact over a 5 -m straight line and performing 10 steps.

RESULTS

Moderate-to-excellent intrasession reliability (intraclass correlation coefficient = 0.60-0.98) was obtained for all the measurements and groups. However, only small to moderate correlations were found between the dynamic and the static measurements of balance for the CP group when performing the One-Leg Stance test with the unimpaired or dominant leg (0.23 < r < 0.30; P < .01). The TW performed over 10 steps revealed more sensitivity to discriminate between CP profiles. Those para-athletes with ataxia/athetosis performed worse in all the tests whereas all CP profiles performed worse than the control group (P < .01).

CONCLUSIONS

Balance performance and postural control are constrained to a higher extent in those with impaired voluntary control due to ataxia or with involuntary contractions of the muscles due to athetosis.

Is impaired coordination related to match physical load in footballers with cerebral palsy of different sport classes?

Impaired coordination is a characteristic feature in cerebral palsy (CP) football players. This study aimed to determine the relationships of three coordination tests with match physical load during competition of para-footballers from different sport classes. Records from 259 para-footballers from 25 national teams were obtained in four international competitions held in 2018 and 2019. The three coordination tests were conducted prior to competition (i.e., rapid heel-toe, side-stepping, and split jumps), and physical match load was recorded by GPS devices during the real game: i.e., maximum/mean, total distance, distance covered at different speed zones, number of accelerations/decelerations at different intensities, and player load. FT1 and FT3 players have the lowest and highest performance in all the coordination tests, respectively, but inconclusive between-groups differences were obtained (p=0.022‒0.238). Split jumps and side-stepping tests are associated with the performance of moderate and high accelerations during competition (r = -0.20‒0.71; p<0.01). Significant correlations (r = 0.36‒0.71; p<0.01) were obtained between all the coordination measures. Coordination tests better discriminate those with more severe impairments and some evidence for the validity of the new CP football sport classes is provided. Further research is necessary to identify the portion of the variance in sports performance that coordination explains.

Validity and Reliability of a Test Battery to Assess Change of Directions with Ball Dribbling in Para-footballers with Cerebral Palsy

The purpose of this study was to evaluate the content and construct validity and between-sessions reliability of four agility tests requiring ball dribbling in football players with cerebral palsy (CP) with implications for classification and training. A sample of 35 football players with CP from three different countries took part in the study. They performed four tests in two sessions 72 h apart: i) 20 m in a straight line, ii) forward slalom with short changes of direction, iii) forward slalom with wide changes of direction and iv) square course. The Kappa coefficient was used to test content validity, obtaining moderate to almost perfect agreement results. Construct validity was also demonstrated with very large to almost perfect correlations between tests and sessions. Good reliability was found using intra-class coefficients (>0.86), standard error of measurement (<10.8%) and Cronbach´s alpha (>0.86). The comparisons between CP profiles (i.e. sport classes) demonstrated that those with mild impairment performed faster, and those with impairment of ataxia and dyskinesia performed worse. The four tests could have applications in classification, but may also be applied by the CP football coaches to improve athlete agility and football skills.

Validation of a Physical Education Teachers' Self-Efficacy Instrument Toward Inclusion of Students With Disabilities

Acquiring specific training in disability seems to be a key aspect for achieving school inclusion. Teachers who receive such prior training would be more prepared to address diversity in the classroom, which could be related to their perception of self-efficacy. The aim of this study was to validate the Spanish version of the Self-Efficacy Scale for Physical Education Teacher Education Majors toward Children with Disabilities (SE-PETE-D). Two hundred and eighteen in-service physical education teachers participated in this study, with a M age = 38.06 years and M teaching  experience = 11.72 years. To obtain the three subscales resulting from intellectual, physical, and visual disabilities, several exploratory and confirmatory factor analyses were conducted. The results supported three independent models made up of three factors (intellectual, physical, and visual disabilities). The structure of the models was invariant with respect to gender, the educational stage in which the teaching was taking place, previous teaching experience, previous training, and previous experience in adapted or inclusive physical activity and sports. The subscales presented high reliability values for Cronbach's alpha, and Omega's index ≥0.81. This study provides evidence of the validity and reliability of an instrument to measure the perceived self-efficacy of physical education teachers to include students with disabilities in their classes and is the first study to be applied with in-service teachers. In addition, some methodological and conceptual limitations of the original scale are identified, opening new lines of work in relation to training situations to assess the perception of self-efficacy or the type of disability.

Manual Dexterity and Intralimb Coordination Assessment to Distinguish Different Levels of Impairment in Boccia Players with Cerebral Palsy

Background

Boccia is a paralympic sport played by athletes with severe neurological impairments affecting all four limbs. Impaired manual dexterity (MD) and intralimb coordination (ILC) may limit individuals’ ability to perform certain activities such as grasping, releasing, or manipulating objects, which are essential tasks for daily life or to participate in para sports such as boccia. However, there are currently no specific instruments available to assess hand–arm coordination in boccia players with severe cerebral palsy (CP).

Purpose

To design new sport-specific coordination tests to assess impaired MD and ILC in boccia players; afterward, quantify to what extent their coordination is impaired compared to a control group (CG) without neurological impairments.

Methods

Seventy-three recreational boccia players with severe CP (BC1: age = 34.01 ± 16.43 years; BC2: age = 33.97 ± 14.29 years), and 19 healthy adults (age = 27.89 ± 7.08 years) completed the test battery. The Box and Block test (BBT) and Box and Ball test (BBLT) were used to assess MD and four tapping tests to assess upper ILC.

Results

Both MD tests were able to discriminate between sport classes. Boccia players obtained better scores in the BBLT in comparison to the BBT, showing that the BBLT had more appropriate testing features. On the other hand, only one of the ILC tests was able to discriminate between sport classes, displaying the highest practical significance (d = −1.12). Participants with CP scored significantly worse in all the coordination tests compared to the CG.

Conclusion

Using sport-specific equipment facilitated grasp function during the MD assessment. Regarding the ILC, the type of movement (continuous vs. discrete) seems to be more relevant for classification than the movement direction (vertical vs. horizontal) or the presence of a ball.

Opioid analgesic use among patients presenting with acute abdominal pain and factors associated with surgical diagnoses

BACKGROUND

The prevalence of chronic opioid use among non-cancer patients presenting with acute abdominal pain (AAP) is unknown. The aim was to characterize opioid use, constipation, diagnoses, and risk factors for surgical diagnoses among non-cancer patients presenting with AAP to an emergency department (ED).

METHODS

We performed a retrospective, observational cohort study of all (n=16,121) adult patients (88% from MN, IA and WI) presenting during 2014 with AAP. We used electronic medical records, and focused on 2352 adults with AAP who underwent abdominal CT scan within 24 hours of presentation. We determined odds ratios of association with constipation and features predicting conditions that may require surgery (surgical diagnosis).

KEY RESULTS

There were 2352 eligible patients; 18.8% were opioid users. Constipation was more frequent in opioid (35.1%) compared to non-opioid users [OR 2.88 (95% CI 2.28, 3.62)]. Prevalence of surgical diagnosis in the opioid and non-opioid users was 35.3% and 41.7% respectively (P=.019). By univariate analysis, age and neutrophil count independently predicted increased risk, and chronic opioid use decreased risk of surgical diagnosis. Internal validation of logistic models using a randomly selected validation subset (25% of entire cohort, 587/2352) showed receiver operating characteristic (ROC) curves for the validation and full cohorts were similar.

CONCLUSIONS AND INFERENCES

Approximately 19% of adults presenting with AAP were opioid users; constipation is almost three times as likely in opioid users compared to non-opioid users presenting with AAP. Factors significantly associated with altered risk of surgical diagnoses were age, opioid use, and neutrophil count.

DFT-D2 simulations of water adsorption and dissociation on the low-index surfaces of mackinawite (FeS)

The adsorption and dissociation of water on mackinawite (layered FeS) surfaces were studied using dispersion-corrected density functional theory (DFT-D2) calculations. The catalytically active sites for H2O and its dissociated products on the FeS {001}, {011}, {100}, and {111} surfaces were determined, and the reaction energetics and kinetics of water dissociation were calculated using the climbing image nudged elastic band technique. Water and its dissociation products are shown to adsorb more strongly onto the least stable FeS{111} surface, which presents low-coordinated cations in the surface, and weakest onto the most stable FeS{001} surface. The adsorption energies decrease in the order FeS{111} > FeS{100} > FeS{011} > FeS{001}. Consistent with the superior reactivity of the FeS{111} surface towards water and its dissociation products, our calculated thermochemical energies and activation barriers suggest that the water dissociation reaction will take place preferentially on the FeS nanoparticle surface with the {111} orientation. These findings improve our understanding of how the different FeS surface structures and the relative stabilities dictate their reactivity towards water adsorption and dissociation.

Catalytic water dissociation by greigite Fe3S4 surfaces: density functional theory study

The iron sulfide mineral greigite, Fe3S4, has shown promising capability as a hydrogenating catalyst, in particular in the reduction of carbon dioxide to produce small organic molecules under mild conditions. We employed density functional theory calculations to investigate the {001},{011} and {111} surfaces of this iron thiospinel material, as well as the production of hydrogen ad-atoms from the dissociation of water molecules on the surfaces. We systematically analysed the adsorption geometries and the electronic structure of both bare and hydroxylated surfaces. The sulfide surfaces presented a higher flexibility than the isomorphic oxide magnetite, Fe3O4, allowing perpendicular movement of the cations above or below the top atomic sulfur layer. We considered both molecular and dissociative water adsorption processes, and have shown that molecular adsorption is the predominant state on these surfaces from both a thermodynamic and kinetic point of view. We considered a second molecule of water which stabilizes the system mainly by H-bonds, although the dissociation process remains thermodynamically unfavourable. We noted, however, synergistic adsorption effects on the Fe3S4{001} owing to the presence of hydroxyl groups. We concluded that, in contrast to Fe3O4, molecular adsorption of water is clearly preferred on greigite surfaces.

Surface and shape modification of mackinawite (FeS) nanocrystals by cysteine adsorption: a first-principles DFT-D2 study

The surface and shape modulation of mackinawite (FeS) nanoparticles by amino acid cysteine adsorption is investigated using a first-principles density functional theory calculations, corrected for dispersion-interactions (DFT-D2).

Methanol formation from CO2catalyzed by Fe3S4{111}: formate versus hydrocarboxyl pathways

Carbon capture and utilisation is one of the most promising techniques to minimize the impact of the increasing amount of carbon dioxide in the atmosphere. Recently, the mineral greigite was shown to be capable of catalysing CO₂conversion, leading to useful small organic molecules. Here, we have carried out a systematic study of the adsorption and selective reduction of CO₂on the Fe₃S₄{111} surface. We have considered both formate and hydrocarboxyl key intermediates, leading to different reaction pathwaysviaEley–Rideal and Langmuir–Hinshelwood mechanisms, and we have built a kinetic model considering the wide range of intermediates in the reaction network. Our results show that the mechanism to produce formic acid takes placeviaformate intermediate mostly on Fe_Asites, while methanol is formedviahydrocarboxyl intermediates on Fe_Bsites. From the kinetic model, we have derived a reaction constant comparison and determined the limiting step rates. The overall process takes place under very mild conditions, requiring only a small energy input that might come from a chemiosmotic potential.

The surface chemistry of NO(x) on mackinawite (FeS) surfaces: a DFT-D2 study

We present density functional theory calculations with a correction for the long-range interactions (DFT-D2) of the bulk and surfaces of mackinawite (FeS), and subsequent adsorption and dissociation of NO(x) gases (nitrogen monoxide (NO) and nitrogen dioxide (NO2)). Our results show that these environmentally important molecules interact very weakly with the energetically most stable (001) surface, but adsorb relatively strongly onto the FeS(011), (100) and (111) surfaces, preferentially at Fe sites via charge donation from these surface species. The NOx species exhibit a variety of adsorption geometries, with the most favourable for NO being the monodentate Fe-NO configuration, whereas NO2 is calculated to form a bidentate Fe-NOO-Fe configuration. From our calculated thermochemical energy and activation energy barriers for the direct dissociation of NO and NO2 on the FeS surfaces, we show that NO prefers molecular adsorption, while dissociative adsorption, i.e. NO2 (ads) → [NO(ads) + O(ads)] is preferred over molecular adsorption for NO2 onto the mackinawite surfaces. However, the calculated high activation barriers for the further dissociation of the second N-O bond to produce either [N(ads) and 2O(ads)] or [N(ads) and O2(ads)] suggest that complete dissociation of NO2 is unlikely to occur on the mackinawite surfaces.

Bio-inspired CO2conversion by iron sulfide catalysts under sustainable conditions

CO₂conversion to small bio-molecules on greigite minerals under room temperature and pressure.

Adsorption of methylamine on mackinawite (FES) surfaces: a density functional theory study

We have used density functional theory calculations to investigate the interaction between methylamine (CH3NH2) and the dominant surfaces of mackinawite (FeS), where the surface and adsorption properties of mackinawite have been characterized using the DFT-D2 method of Grimme. Our calculations show that while the CH3NH2 molecule only interacts weakly with the most stable FeS(001), it adsorbs relatively strongly on the FeS(011) and FeS(100) surfaces releasing energies of 1.26 eV and 1.51 eV, respectively. Analysis of the nature of the bonding reveals that the CH3NH2 molecule interacts with the mackinawite surfaces through the lone-pair of electrons located on the N atom. The electron density built up in the bonding region between N and Fe is very much what one would expect of covalent type of bonding. We observe no significant adsorption-induced changes of the FeS surface structures, suggesting that amine capping agents would not distort the FeS nanoparticle surfaces required for active heterogeneous catalytic reactions. The vibrational frequencies and the infrared spectra of adsorbed methylamine have been calculated and assignments for vibrational modes are used to propose a kinetic model for the desorption process, yielding a simulated temperature programmed desorption with a relative desorption temperature of <140 K at the FeS(011) surface and <170 K at FeS(100) surface.

A comparative DFT study of the mechanical and electronic properties of greigite Fe3S4 and magnetite Fe3O4

Greigite (Fe3S4) and its analogue oxide, magnetite (Fe3O4), are natural minerals with an inverse spinel structure whose atomic-level properties may be difficult to investigate experimentally. Here, [D. Rickard and G. W. Luther, Chem. Rev. 107, 514 (2007)] we have calculated the elastic constants and other macroscopic mechanical properties by applying elastic strains on the unit cells. We also have carried out a systematic study of the electronic properties of Fe3S4 and Fe3O4, where we have used an ab initio method based on spin-polarized density functional theory with the on-site Coulomb repulsion approximation (Ueff is 1.0 and 3.8 eV for Fe3S4 and Fe3O4, respectively). Comparison of the properties of Fe3S4 and Fe3O4 shows that the sulfide is more covalent than the oxide, which explains the low magnetization of saturation of greigite cited in several experimental reports.

Surveillance for MDR-TB: is there an obligation to ensure treatment for individuals identified with MDR-TB?

This article raises ethical issues that result if individuals, during the course of research to measure the prevalence of drug-resistant tuberculosis, are identified with the disease but are not provided with or referred for appropriate treatment. It draws attention to and applauds recently published World Health Organization guidelines on the subject. Questions posed are: 1) Should treatment be provided for individuals identified through surveillance projects for MDR-TB, whatever their purpose (specific research or 'routine' national prevalence studies)? 2) If treatment availability is a problem, who is responsible for assuring this?

The Levels of Inflammatory Markers in the Treatment of Stroke study (LIMITS): inflammatory biomarkers as risk predictors after lacunar stroke

BACKGROUND

Inflammation is increasingly recognised as playing a central role in atherosclerosis, and peripheral blood markers of inflammation have been associated with incident and recurrent cardiac events. The relationship of these potentially modifiable risk markers to prognosis after ischaemic stroke is less clear. The Levels of Inflammatory Markers in the Treatment of Stroke (LIMITS) study will address hypotheses related to the role of inflammatory markers in secondary stroke prevention in an efficient manner using the well-established framework of the Secondary Prevention of Small Subcortical Strokes (SPS3) trial (NCT00059306).

METHODS

SPS3 is an ongoing Phase III multicentre secondary prevention trial focused on preventing recurrent stroke in patients with small vessel ischaemic stroke, or lacunes. In SPS3, patients are assigned in a factorial design to aspirin vs. aspirin plus clopidogrel, and to usual vs. aggressive blood pressure targets. The purpose of LIMITS is to determine whether serum levels of inflammatory markers - including high-sensitivity C-reactive protein, serum amyloid A, CD40 ligand, and monocyte chemoattractant protein-1 - predict recurrent stroke and other vascular events among lacunar stroke patients. The project will also determine whether these markers predict which people will respond best to dual antiplatelet therapy with clopidogrel and aspirin, as well the relationship to cognitive function.

ANALYSIS

plan Multivariable Cox proportional hazard regression modeling will be used to estimate hazard ratios for the effect of marker levels on risk of recurrent stroke and other outcomes after adjusting for additional potential risk factors, including age, gender, ethnicity, treatment arm, and traditional stroke risk factors. Interactions between marker levels and treatment assignment for both arms of the SPS3 study will be assessed. Observations will be censored at the time of last follow-up visit.

CONCLUSIONS

LIMITS represents an efficient approach to the identification of novel inflammatory biomarkers for use in risk prediction and treatment selection in patients with small vessel disease.

Characterization of CSF hydrodynamics in the presence and absence of tonsillar ectopia by means of computational flow analysis

BACKGROUND AND PURPOSE

Phase-contrast MR imaging (PCMR) has only partially characterized cyclic CSF flow and pressure, which, hypothetically, have a role in the pathogenesis of syrinx and symptoms in the Chiari I malformation. Our goal was to use computational flow analysis (CFA) to better understand CSF hydrodynamics.

MATERIALS AND METHODS

High-resolution MR images were obtained in a healthy volunteer and a patient with Chiari I malformation. With standard segmentation and discretization techniques, 3D models of the subarachnoid space, cerebellum, and spinal canal were created. CSF flow during systole and diastole were simulated with the boundary element method in the models. CSF velocities and pressures computed in the patient with Chiari I malformation were compared with those in the healthy volunteer. Flow patterns were also compared with PCMR results for validation of the technique.

RESULTS

The CFA and PCMR results agreed well. Inhomogeneous flow patterns characterized by fluid jets anterior and lateral to the spinal cord were demonstrated in both the Chiari I and volunteer models by CFA. Significant circumferential velocities were evident, suggesting swirling flow in the spinal canal. Higher magnitude jets were found in the patient with Chiari I than in the healthy volunteer. Relatively even pressure gradients were found along the spinal canal in both cases, with a 50% steeper gradient in the patient with Chiari I malformation.

CONCLUSIONS

Circumferential velocities and pressure gradients in the spinal canal, which may be clinically relevant to Chiari I and other malformations, can be obtained by CFA in patient-specific geometries.

Catecholamine levels in practitioners of the transcendental meditation technique

With the aim of evaluating the sympathetic-adrenal medulla system in subjects practicing transcendental meditation (TM), their plasma catecholamine levels were determined at two different times of day. The study group consisted of 19 subjects who regularly practice either TM or Sidhi-TM technique, with a control group made up of 16 healthy subjects who had not previously used any relaxation technique. Catecholamine plasma levels were determined by high performance liquid chromatography, at 0900 and 2000 h. Morning and evening norepinephrine (NE) levels and morning epinephrine (E) levels were significantly lower in the TM group than in the control subjects (morning NE levels, pg/ml, mean+/-S.E.: TM group 136.6+/-13.0, control 236.8+/-21.0, P=.0001; evening NE levels: TM group 119.7+/-10.8, control 175.6+/-17.4, P=.009; morning E levels, pg/ml: TM group 140.2+/-10.6, control 196.7+/-23.8, P=.019). No differences were recorded for evening E levels and dopamine (DA) levels. No significant differences were found for catecholamine levels measured at different times of day in the TM group, demonstrating a lack of daily hormonal rhythm. Anxiety levels were similar in both groups. Based on the results obtained, it can be considered that the regular practice of TM has a significant effect on the sympathetic-adrenal medulla system. A low hormonal response to daily stress caused by sympathetic tone regulation through regular TM could explain our results, as well as the physiological and other effects related to the field of health described in those who practice meditation.

ACTH and beta-endorphin in transcendental meditation

We have evaluated the effect of Transcendental Meditation (TM) on the hypothalamo-hypophyseal-adrenal axis diurnal rhythms through the determination of hormone levels. Blood samples were taken at 0900 hours. and at 2000 hours. These samples were taken from 18 healthy volunteers who regularly practice TM and from nine healthy non-meditators. Cortisol, beta-endorphin, and adrenocorticotropic hormone (ACTH) were measured at both hours. TM practitioners showed no diurnal rhythm for ACTH and for beta-endorphin (ACTH, pg/mL, mean +/- SE; 13.8+/-1.2 - 12.1+/-1.5/beta-endorphin, pg/mL; 14.4+/-1.5 - 17.2+/-1.9, at 0900 hours and 2000 hours, respectively), in contrast to control subjects, who showed normal diurnal rhythm for these hormones and for cortisol (ACTH, pg/mL; 19.4+/-1.9 - 11.9+/-2.2/beta-endorphin, pg/mL; 25.4+/-1.7 - 17.7+/-1.1/Cortisol, ng/mL; 201.4+/-13.2 - 71.3+/-6.5, at 0900-2000 hours, respectively, p < 0.01 in the three cases). Practitioners of TM with similar anxiety levels to those of the control group showed a different pattern in the daytime secretion of pituitary hormones. TM thus appears to have a significant effect on the neuroendocrine axis. Because cortisol levels had a normal pattern in the TM group, these results may be due to a change in feedback sensitivity caused by this mental technique.

Role of magnetic resonance imaging in predicting relapse in residual masses after treatment of lymphoma

PURPOSE

This prospective study of patients treated at the Royal Marsden Hospital Lymphoma Unit was designed to evaluate the role of magnetic resonance imaging (MRI) in the assessment of residual masses evident on computed tomographic (CT) scanning following treatment of lymphoma.

PATIENTS AND METHODS

All patients had MRI, gallium-67 single-photon emission CT (67Ga SPECT), and erythrocyte sedimentation rate (ESR) performed within 3 months of completing therapy. Patients were monitored for 1 year posttreatment and observed for signs of relapse. Investigation results were correlated with disease status, and the sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) calculated. Time-to-relapse curves were derived and the log-rank test used to determine whether patients with a positive result were more likely to have a relapse within the mass than those with a negative result.

RESULTS

Thirty-four patients were studied, 14 of whom relapsed, 11 within the area of residual mass. Overall, MRI had a high specificity (90%), PPV (71%), and NPV (75%), but poor sensitivity (45%). The results for 67Ga SPECT were similar, apart from lower sensitivity (33%). ESR had inferior performance in predicting relapse compared with the other tests. MRI was the only investigation to show statistical significance (P = .14) in predicting relapse, and this was particularly evident in Hodgkin's lymphoma (P = .003). Combining results of 67Ga SPECT and MRI did not improve predictive power.

CONCLUSION

These data demonstrate that MRI is a valuable tool in the setting of a residual mass after treatment, giving clinically useful prognostic information. 67Ga SPECT also has a role, but is less effective in predicting relapse than MRI.

EPIC: an effective low toxicity regimen for relapsing lymphoma

We have treated 40 patients was relapsed or resistant lymphoma with the combination of Etoposide, Prednisolone, Ifosfamide and Cisplatin (EPIC). Complete response was obtained in 11 patients (28%) with an overall response of 58%. The presence of bulky disease (P < 0.005), elevated LDH serum levels (P < 0.005), response to prior chemotherapy (P < 0.01) and B symptoms (P < 0.005) were significantly associated with response. However on multivariate analysis only the presence of bulky disease and of B symptoms were independent adverse factors for response and for survival. The regimen was well tolerated with myelosuppression being the most common toxicity. Leucopenia < or 1,000 microliters-1 and thrombocytopenia < or = 25,000 microliters-1 developed in 27% and 4% of cycles respectively. There were no treatment related deaths. The EPIC regimen has equivalent activity to other reported cisplatin based regimens used in the treatment of recurrent lymphoma, but is associated with lower treatment related morbidity and mortality.

2'-Chlorodeoxyadenosine: evaluation of a novel predominantly lymphocyte selective agent in lymphoid malignancies

2'-Chlorodeoxyadenosine (2CDA) is a purine analogue selectively active against both resting and dividing lymphoid cells. Twenty-one patients with a variety of previously treated lymphoid malignancies received a total of 41 courses of 2CDA (0.1-0.15 mg/kg/day over 7 days continuous intravenous infusion) on compassionate grounds. The profile of the patient population was as follows: low grade non-Hodgkin's lymphoma (NHL) = 8, intermediate grade NHL = 2, transformed (intermediate grade NHL) = 6, Hodgkin's disease = 1, lymphoplasmacytoid NHL = 3 and lymphoblastic NHL = 1. The overall response rate was 53%, with three patients attaining complete remission (CR) and eight partial remission (PR). Three of 16 patients with primary resistant or resistant recurrent disease entered either CR (1) or PR (2). Ten patients had no response or progressive disease. The latter group was comprised of patients who had extensively pre-treated lymphoplasmacytoid tumours and/or poor performance status (WHO grades 2-4). The median duration of response is 6 months (range 1 to 12 months). Treatment was well tolerated and the chief toxicities were leucopenia and thrombocytopenia which were most pronounced when there was bone marrow involvement. As a result of dose limiting myelotoxicity, a dose escalation to 0.15 mg/kg/day was possible on just three occasions. These data confirm other reports of the activity of 2CDA in low grade NHL and indicate it may have activity in Hodgkin's disease. There was no demonstrable activity in poor performance status patients or those with extensively pre-treated lymphoplasmacytoid tumours.

Spinal myoclonus: successful treatment with the combination of sodium valproate and L-5-hydroxytryptophan

We describe a 37-year-old man with spinal segmental myoclonus characterized by symmetric, rhythmic contractions of the abdomen with a frequency ranging between 100 and 150/min. The combination of sodium valproate and L-5-hydroxytryptophan was useful to control the myoclonus. We comment on the possible role of the serotonergic system in this syndrome.

Insulin-like growth factor-1 increases the mitogenic response of human peripheral blood lymphocytes to phytohemagglutinin

Receptors for insulin and insulin-like growth factor-1 (IGF-1) have been demonstrated on activated T-lymphocytes. The question is whether receptors for insulin or IGF-1 have any function in these cells. In this study we demonstrate that the concentration of IGF-1 in commercial samples of fetal calf serum is about 70 times that of insulin. Moreover, antibodies binding IGF-1 reduce responses of human peripheral blood mononuclear cells to PHA by about 50%, whereas antibodies to insulin have no demonstrable effect. These observations suggest that binding of IGF-1 to specific receptors contributes to the proliferative responses of activated T-lymphocytes.