MRSA/MSSA causing infections: prevalence of mecA gene

Introduction Staphylococcus aureus is part of the human flora, present in the skin and mucous membranes but can become pathogenic, causing a wide spectrum of infections that were initially treated with penicillin. However, were observed some strains with resistance to this antibiotic and, therefore was developed a new antibiotic, the methicillin. After its introduction, arose the first S. aureus with resistance to methicillin (MRSA) due to the presence of a gene known as mecA that encodes an altered penicillin binding protein (PBP2a). In Europe, it is estimated that MRSA are associated to 44% of hospital acquired infections and its mortality rate is around 20%.

Objectives Prevalence of MRSA strains in different types of infection in Coimbra district.

Methodology Were analysed a total of 539 isolates of S. aureus previously characterized to the antibiotic susceptibility profile in the Hospital and University Center of Coimbra. Through the minimum inhibitory concentration (MIC) of oxacillin we classified our strains into MRSA and S. aureus methicillin-sensitive (MSSA); simultaneously, the mecA gene was detected by Polymerase Chain Reaction (PCR).

Results Of the 539 isolates, 49% were considered MRSA and 51% MSSA. All MRSA isolates express the mecA gene, but from the total of 276 MSSA, 191 show this gene but do not express it. MRSA isolates were mostly from respiratory tract samples (48%) and blood cultures (21%) while MSSA were isolated in skin and soft tissue samples (35%).

Conclusion MRSA are considered one of the primary pathogens for the development of pneumonia and septicaemia due to its highly virulent potential and the increasing expression of genetic determinants of antimicrobial resistance. Therefore, infections caused by MRSA continue with highly representability in the clinical context and their dissemination is a public health problem.

Associations between children's family environment, spontaneous brain oscillations, and emotional and behavioral problems

The family environment in childhood has a strong effect on mental health outcomes throughout life. This effect is thought to depend at least in part on modifications of neurodevelopment trajectories. In this exploratory study, we sought to investigate whether a feasible resting-state fMRI metric of local spontaneous oscillatory neural activity, the fractional amplitude of low-frequency fluctuations (fALFF), is associated with the levels of children's family coherence and conflict. Moreover, we sought to further explore whether spontaneous activity in the brain areas influenced by family environment would also be associated with a mental health outcome, namely the incidence of behavioral and emotional problems. Resting-state fMRI data from 655 children and adolescents (6-15 years old) were examined. The quality of the family environment was found to be positively correlated with fALFF in the left temporal pole and negatively correlated with fALFF in the right orbitofrontal cortex. Remarkably, increased fALFF in the temporal pole was associated with a lower incidence of behavioral and emotional problems, whereas increased fALFF in the orbitofrontal cortex was correlated with a higher incidence.

Predictive saccades in children and adults: A combined fMRI and eye tracking study

Saccades were assessed in 21 adults (age 24 years, SD = 4) and 15 children (age 11 years, SD = 1), using combined functional magnetic resonance imaging (fMRI) and eye-tracking. Subjects visually tracked a point on a horizontal line in four conditions: time and position predictable task (PRED), position predictable (pPRED), time predictable (tPRED) and visually guided saccades (SAC). Both groups in the PRED but not in pPRED, tPRED and SAC produced predictive saccades with latency below 80 ms. In task versus group comparisons, children's showed less efficient learning compared to adults for predictive saccades (adults = 48%, children = 34%, p = 0.05). In adults brain activation was found in the frontal and occipital regions in the PRED, in the intraparietal sulcus in pPRED and in the frontal eye field, posterior intraparietal sulcus and medial regions in the tPRED task. Group-task interaction was found in the supplementary eye field and visual cortex in the PRED task, and the frontal cortex including the right frontal eye field and left frontal pole, in the pPRED condition. These results indicate that, the basic visuomotor circuitry is present in both adults and children, but fine-tuning of the activation according to the task temporal and spatial demand mature late in child development.

Activity of Antarctic fungi extracts against phytopathogenic bacteria

This study aims to obtain secondary metabolites extracts from filamentous fungi isolated from soil and marine sediments from Antarctic ecosystems and to assess its potential antibacterial activity on Xanthomonas euvesicatoria and Xanthomonas axonopodis pv. passiflorae (phytopathogenic bacteria causing diseases in pepper and tomato and passionfruit, respectively). Among the 66 crude intracellular and extracellular extracts obtained from fungi recovered from soil and 79 obtained from marine sediment samples, 25 showed the ability to prevent the growth of X. euvesicatoria in vitro and 28 showed the ability to prevent the growth of X. axonopodis pv. passiflorae in vitro. Intracellular and extracellular extracts from soil fungi inhibited around 97% of X. euvesicatoria and 98% of X. axonopodis pv. passiflorae at 2·1 mg ml^-1 . The average inhibition rates against X. euvesicatoria and X. axonopodis pv. passiflorae for intracellular and extracellular extracts from marine sediments fungi were around 96 and 97%, respectively, at 3·0 mg ml^-1 . Extracts containing secondary metabolites with antimicrobial activity against X. euvesicatoria and X. axonopodis pv. passiflorae were obtained, containing possible substitutes for the products currently used to control these phytopathogens.

SIGNIFICANCE AND IMPACT OF THE STUDY

Micro-organisms from extreme ecosystems, such as the Antarctic ecosystem, need to survive in harsh conditions with low temperatures, low nutrients and high UV radiation. Micro-organisms adapt to these conditions evolving diverse biochemical and physiological adaptations essential for survival. All this makes these micro-organisms a rich source of novel natural products based on unique chemical scaffolds. Discovering novel bioactive compounds is essential because of the rise in antibiotic-resistant micro-organisms and the emergence of new infections. Fungi from Antarctic environments have been proven to produce bioactive secondary metabolites against various micro-organisms, but few studies have shown activity against Xanthomonas phytopathogens.

Association between abnormal brain functional connectivity in children and psychopathology: A study based on graph theory and machine learning

OBJECTIVES

One of the major challenges facing psychiatry is how to incorporate biological measures in the classification of mental health disorders. Many of these disorders affect brain development and its connectivity. In this study, we propose a novel method for assessing brain networks based on the combination of a graph theory measure (eigenvector centrality) and a one-class support vector machine (OC-SVM).

METHODS

We applied this approach to resting-state fMRI data from 622 children and adolescents. Eigenvector centrality (EVC) of nodes from positive- and negative-task networks were extracted from each subject and used as input to an OC-SVM to label individual brain networks as typical or atypical. We hypothesised that classification of these subjects regarding the pattern of brain connectivity would predict the level of psychopathology.

RESULTS

Subjects with atypical brain network organisation had higher levels of psychopathology (p < 0.001). There was a greater EVC in the typical group at the bilateral posterior cingulate and bilateral posterior temporal cortices; and significant decreases in EVC at left temporal pole.

CONCLUSIONS

The combination of graph theory methods and an OC-SVM is a promising method to characterise neurodevelopment, and may be useful to understand the deviations leading to mental disorders.

Cognitive performance in transient global hypoxic brain injury due to moderate drowning

INTRODUCTION

Drowning is a serious and frequently neglected public health threat. Primary respiratory impairment after submersion often leads to brain dysfunction. Depending on the period of global hypoxia (respiratory failure), clinical aspects of neurological dysfunction are evident on the first evaluation after the water rescue. Nowadays, many neuropsychological assessments after drowning are inconclusive, with some studies reporting only minor neurological or cognitive impairments. The aim of this study is to identify measures in neuropsychological tests that most contribute to classify volunteers as moderate drowning subjects or healthy controls. To the best of our knowledge, this study is the first neuropsychological prospective case-control study of moderate drowning in a country with large coastal cities.

METHOD

Fifteen moderate drowning patients (DP), who met the inclusion criteria, were compared with 18 healthy controls (HC). All subjects were assessed on memory, learning, visual spatial ability, executive function, attention, and general intellectual functioning and underwent structural magnetic resonance (MR) imaging of the brain at 3.0 T, in order to exclude subjects with anatomic abnormalities.

RESULTS

Neuropsychological tests assessing learning, execution function, and verbal fluency-Rey Auditory Verbal Learning Test (RAVLT) general learning ability, Digit Span total, Phonological Verbal Fluency (total FAS correct), and Brief Visuospatial Memory Test Revised (BVMT) correct recognition-have the strongest discriminating ability, using predictive models via the partial least squares (PLS) approach for data classification, while the other tests have shown similar predictive values between groups.

CONCLUSIONS

Learning, execution function, and verbal fluency domains were the most critically affected domains. Serious impairments in the same domains have already been reported in severe drowning cases, and we hypothesize that subtle alterations found in moderate drowning cases, although not sufficient to be detected in daily routine, may possibly have a negative impact on cognitive reserve.

Substantia nigra fractional anisotropy is not a diagnostic biomarker of Parkinson's disease: A diagnostic performance study and meta-analysis

OBJECTIVES

Our goal was to estimate the diagnostic accuracy of substantia nigra fractional anisotropy (SN-FA) for Parkinson's disease (PD) diagnosis in a sample similar to the clinical setting, including patients with essential tremor (ET) and healthy controls (HC). We also performed a systematic review and meta-analysis to estimate mean change in SN-FA induced by PD and its diagnostic accuracy.

METHODS

Our sample consisted of 135 subjects: 72 PD, 21 ET and 42 HC. To address inter-scanner variability, two 3.0-T MRI scans were performed. MRI results of this sample were pooled into a meta-analysis that included 1,432 subjects (806 PD and 626 HC). A bivariate model was used to evaluate diagnostic accuracy measures.

RESULTS

In our sample, we did not observe a significant effect of disease on SN-FA and it was uninformative for diagnosis. The results of the meta-analysis estimated a 0.03 decrease in mean SN-FA in PD relative to HC (CI: 0.01-0.05). However, the discriminatory capability of SN-FA to diagnose PD was low: pooled sensitivity and specificity were 72 % (CI: 68-75) and 63 % (CI: 58-70), respectively. There was high heterogeneity between studies (I² = 91.9 %).

CONCLUSIONS

SN-FA cannot be used as an isolated measure to diagnose PD.

KEY POINTS

• SN-FA appears insufficiently sensitive and specific to diagnose PD. • Radiologists must be careful when translating mean group results to clinical practice. • Imaging protocol and analysis standardization is necessary for developing reproducible quantitative biomarkers.

Connectome hubs at resting state in children and adolescents: Reproducibility and psychopathological correlation

Functional brain hubs are key integrative regions in brain networks. Recently, brain hubs identified through resting-state fMRI have emerged as interesting targets to increase understanding of the relationships between large-scale functional networks and psychopathology. However, few studies have directly addressed the replicability and consistency of the hub regions identified and their association with symptoms. Here, we used the eigenvector centrality (EVC) measure obtained from graph analysis of two large, independent population-based samples of children and adolescents (7–15 years old; total N = 652; 341 subjects for site 1 and 311 for site 2) to evaluate the replicability of hub identification. Subsequently, we tested the association between replicable hub regions and psychiatric symptoms. We identified a set of hubs consisting of the anterior medial prefrontal cortex and inferior parietal lobule/intraparietal sulcus (IPL/IPS). Moreover, lower EVC values in the right IPS were associated with psychiatric symptoms in both samples. Thus, low centrality of the IPS was a replicable sign of potential vulnerability to mental disorders in children. The identification of critical and replicable hubs in functional cortical networks in children and adolescents can foster understanding of the mechanisms underlying mental disorders.

Steering microtubule shuttle transport with dynamically controlled magnetic fields

Nanoscale control of matter is critical to the design of integrated nanosystems. Here, we describe a method to dynamically control directionality of microtubule (MT) motion using programmable magnetic fields. MTs are combined with magnetic quantum dots (i.e., MagDots) that are manipulated by external magnetic fields provided by magnetic nanowires. MT shuttles thus undergo both ATP-driven and externally-directed motion with a fluorescence component that permits simultaneous visualization of shuttle motion. This technology is used to alter the trajectory of MTs in motion and to pin MT motion. Such an approach could be used to evaluate the MT-kinesin transport system and could serve as the basis for improved lab-on-a-chip technologies based on MT transport.

Metamemory and aging: Psychometric properties of the Brazilian version of the Multifactorial Memory Questionnaire for elderly

Metamemory measures provide subjective memory information and are relevant to investigate memory ability in aging. However, there is a lack of metamemory instruments available in Brazil.

Independent Component versus Local Sparse Component Analysis in Resting State fMRI

Independent Component Analysis (ICA) algorithms are potentially powerful ways of localizing sources of cerebral activity in resting state functional Magnetic Resonance Imaging (fMRI). But the assumptions underling the nature of identified sources limits this tool. By creating local one-dimensional approximations, Local Sparse Component Analysis (LSCA) can separate contiguous sources on the basis of their sparse representation into smoothness spaces via the 3D wavelet transformation. In this paper we systematically compare Probabilistic ICA (PICA) and LSCA for analyzing resting state fMRI across healthy participants. We show that the PICA sources usually representing biologically plausible components can in fact be decomposed into several LSCA sources that are not necessarily independent from each other. In addition, we show that LSCA identifies sources that approximate much better the local variations of the blood oxygenation level-dependent (BOLD) signal than PICA sources.

Default mode network maturation and psychopathology in children and adolescents

BACKGROUND

The human default mode (DMN) is involved in a wide array of mental disorders. Current knowledge suggests that mental health disorders may reflect deviant trajectories of brain maturation.

METHOD

We studied 654 children using functional magnetic resonance imaging (fMRI) scans under a resting-state protocol. A machine-learning method was used to obtain age predictions of children based on the average coefficient of fractional amplitude of low frequency fluctuations (fALFFs) of the DMN, a measure of spontaneous local activity. The chronological ages of the children and fALFF measures from regions of this network, the response and predictor variables were considered respectively in a Gaussian Process Regression. Subsequently, we computed a network maturation status index for each subject (actual age minus predicted). We then evaluated the association between this maturation index and psychopathology scores on the Child Behavior Checklist (CBCL).

RESULTS

Our hypothesis was that the maturation status of the DMN would be negatively associated with psychopathology. Consistent with previous studies, fALFF significantly predicted the age of participants (p < .001). Furthermore, as expected, we found an association between the DMN maturation status (precocious vs. delayed) and general psychopathology scores (p = .011).

CONCLUSIONS

Our findings suggest that child psychopathology seems to be associated with delayed maturation of the DMN. This delay in the neurodevelopmental trajectory may offer interesting insights into the pathophysiology of mental health disorders.

Temporal stability of network centrality in control and default mode networks: Specific associations with externalizing psychopathology in children and adolescents

Abnormal connectivity patterns have frequently been reported as involved in pathological mental states. However, most studies focus on "static," stationary patterns of connectivity, which may miss crucial biological information. Recent methodological advances have allowed the investigation of dynamic functional connectivity patterns that describe non-stationary properties of brain networks. Here, we introduce a novel graphical measure of dynamic connectivity, called time-varying eigenvector centrality (tv-EVC). In a sample 655 children and adolescents (7-15 years old) from the Brazilian "High Risk Cohort Study for Psychiatric Disorders" who were imaged using resting-state fMRI, we used this measure to investigate age effects in the temporal in control and default-mode networks (CN/DMN). Using support vector regression, we propose a network maturation index based on the temporal stability of tv-EVC. Moreover, we investigated whether the network maturation is associated with the overall presence of behavioral and emotional problems with the Child Behavior Checklist. As hypothesized, we found that the tv-EVC at each node of CN/DMN become more stable with increasing age (P < 0.001 for all nodes). In addition, the maturity index for this particular network is indeed associated with general psychopathology in children assessed by the total score of Child Behavior Checklist (P = 0.027). Moreover, immaturity of the network was mainly correlated with externalizing behavior dimensions. Taken together, these results suggest that changes in functional network dynamics during neurodevelopment may provide unique insights regarding pathophysiology.

Long-term structural changes after mTBI and their relation to post-concussion symptoms

PRIMARY OBJECTIVE

To investigate sustained structural changes in the long-term (>1 year) after mild traumatic brain injury (mTBI) and their relationship to ongoing post-concussion syndrome (PCS).

RESEARCH DESIGN

Morphological and structural connectivity magnetic resonance imaging (MRI) data were acquired from 16 participants with mTBI and nine participants without previous head injury.

MAIN OUTCOMES AND RESULTS

Participants with mTBI had less prefrontal grey matter and lower fractional anisotropy (FA) in the anterior corona radiata and internal capsule. Furthermore, PCS severity was associated with less parietal lobe grey matter and lower FA in the corpus callosum.

CONCLUSIONS

There is evidence for both white and grey matter damage in participants with mTBI over 1 year after injury. Furthermore, these structural changes are greater in those that report more PCS symptoms, suggesting a neurophysiological basis for these persistent symptoms.

Relationship Between Surface-Based Brain Morphometric Measures and Intelligence in Autism Spectrum Disorders: Influence of History of Language Delay

Autism spectrum disorders (ASD) are a group of conditions that show abnormalities in the neuroanatomy of multiple brain regions. The variability in the development of intelligence and language among individuals on the autism spectrum has long been acknowledged, but it remains unknown whether these differences impact on the neuropathology of ASD. In this study, we aimed to compare associations between surface-based regional brain measures and general intelligence (IQ) scores in ASD individuals with and without a history of language delay. We included 64 ASD adults of normal intelligence (37 without a history of language delay and 27 with a history of language delay and 80 neurotypicals). Regions with a significant association between verbal and nonverbal IQ and measures of cortical thickness (CT), surface area, and cortical volume were first identified in the combined sample of individuals with ASD and controls. Thicker dorsal frontal and temporal cortices, and thinner lateral orbital frontal and parieto-occipital cortices were associated with greater and lower verbal IQ scores, respectively. Correlations between cortical volume and verbal IQ were observed in similar regions as revealed by the CT analysis. A significant difference between ASD individuals with and without a history of language delay in the association between CT and verbal IQ was evident in the parieto-occipital region. These results indicate that ASD subgroups defined on the basis of differential language trajectories in childhood can have different associations between verbal IQ and brain measures in adulthood despite achieving similar levels of cognitive performance.

Local dimension-reduced dynamical spatio-temporal models for resting state network estimation

To overcome the limitations of independent component analysis (ICA), today’s most popular analysis tool for investigating whole-brain spatial activation in resting state functional magnetic resonance imaging (fMRI), we present a new class of local dimension-reduced dynamical spatio-temporal model which dispenses the independence assumptions that severely limit deeper connectivity descriptions between spatial components. The new method combines novel concepts of group sparsity with contiguity-constrained clusterization to produce physiologically consistent regions of interest in illustrative fMRI data whose causal interactions may then be easily estimated, something impossible under the usual ICA assumptions.

Local sparse component analysis for blind source separation: an application to resting state FMRI

We propose a new Blind Source Separation technique for whole-brain activity estimation that best profits from FMRI's intrinsic spatial sparsity. The Local Sparse Component Analysis (LSCA) combines wavelet analysis, group-separable regularizers, contiguity-constrained clusterization and principal components analysis (PCA) into a unique spatial sparse representation of FMRI images towards efficient dimensionality reduction without sacrificing physiological characteristics by avoiding artificial stochastic model constraints. The LSCA outperforms classical PCA source reconstruction for artificial data sets over many noise levels. A real FMRI data illustration reveals resting-state activities in regions hard to observe, such as thalamus and basal ganglia, because of their small spatial scale.

Multimodal imaging of mild traumatic brain injury and persistent postconcussion syndrome

BACKGROUND

Persistent postconcussion syndrome (PCS) occurs in around 5-10% of individuals after mild traumatic brain injury (mTBI), but research into the underlying biology of these ongoing symptoms is limited and inconsistent. One reason for this could be the heterogeneity inherent to mTBI, with individualized injury mechanisms and psychological factors. A multimodal imaging study may be able to characterize the injury better.

AIM

To look at the relationship between functional (fMRI), structural (diffusion tensor imaging), and metabolic (magnetic resonance spectroscopy) data in the same participants in the long term (>1 year) after injury. It was hypothesized that only those mTBI participants with persistent PCS would show functional changes, and that these changes would be related to reduced structural integrity and altered metabolite concentrations.

METHODS

Functional changes associated with persistent PCS after mTBI (>1 year postinjury) were investigated in participants with and without PCS (both n = 8) and non-head injured participants (n = 9) during performance of working memory and attention/processing speed tasks. Correlation analyses were performed to look at the relationship between the functional data and structural and metabolic alterations in the same participants.

RESULTS

There were no behavioral differences between the groups, but participants with greater PCS symptoms exhibited greater activation in attention-related areas (anterior cingulate), along with reduced activation in temporal, default mode network, and working memory areas (left prefrontal) as cognitive load was increased from the easiest to the most difficult task. Functional changes in these areas correlated with reduced structural integrity in corpus callosum and anterior white matter, and reduced creatine concentration in right dorsolateral prefrontal cortex.

CONCLUSION

These data suggest that the top-down attentional regulation and deactivation of task-irrelevant areas may be compensating for the reduction in working memory capacity and variation in white matter transmission caused by the structural and metabolic changes after injury. This may in turn be contributing to secondary PCS symptoms such as fatigue and headache. Further research is required using multimodal data to investigate the mechanisms of injury after mTBI, but also to aid individualized diagnosis and prognosis.

Small calcified lesions suggestive of neurocysticercosis are associated with mesial temporal sclerosis

Recent studies have suggested a possible relationship between temporal lobe epilepsy with mesial temporal sclerosis (MTS) and neurocysticercosis (NC). We performed a case-control study to evaluate the association of NC and MTS.

METHOD

We randomly selected patients with different epilepsy types, including: MTS, primary generalized epilepsy (PGE) and focal symptomatic epilepsy (FSE). Patients underwent a structured interview, followed by head computed tomography (CT). A neuroradiologist evaluated the scan for presence of calcified lesions suggestive of NC. CT results were matched with patients' data.

RESULTS

More patients in the MTS group displayed calcified lesions suggestive of NC than patients in the other groups (p=0.002). On multivariate analysis, MTS was found to be an independent predictor of one or more calcified NC lesions (p=0.033).

CONCLUSION

After controlling for confounding factors, we found an independent association between NC calcified lesions and MTS.

Age effects on the default mode and control networks in typically developing children

BACKGROUND

The investigation of neurodevelopment during late childhood and pre-adolescence has recently attracted a great deal of interest in the field of neuroimaging. One promising topic in this field is the formation of brain networks in healthy subjects. The integration between neural modules characterizes the ability of the network to process information globally. Although many fMRI-based neurodevelopment studies can be found in the literature, the analyses of very large samples (on the order of hundreds of subjects) that focus on the late childhood/pre-adolescence period and resting state fMRI are scarce, and most studies have focused solely on North American and European populations.

AIMS

In this study, we present a descriptive investigation of the developmental formation of the Default Mode Network and the Control Network based on a Brazilian, cross-sectional community sample of 447 typically developing subjects aged 7-15 years old.

METHODS

Resting state fMRI data were acquired using two MRI systems from the same manufacturer using the same acquisition parameters. We estimated the age effects on the strength of the links (between brain regions) and the network features (graph descriptors: degree and eigenvector centrality).

RESULTS

Our findings showed an increase in the antero-posterior connectivity in both studied networks during brain development. The graph analyses showed an increase in centrality with age for most regions in the Default Mode Network and the dorsal anterior and posterior cingulate, the right anterior insula and the left posterior temporal cortex in the Control Network.

CONCLUSION

We conclude that the period of 7-15 years of age is crucial for the development of both the Default Mode and Control networks, with integration between the posterior and anterior neuronal modules and an increase in the centrality measures of the hub regions.

Right inferior frontal gyrus activation is associated with memory improvement in patients with left frontal low-grade glioma resection

Patients with low-grade glioma (LGG) have been studied as a model of functional brain reorganization due to their slow-growing nature. However, there is no information regarding which brain areas are involved during verbal memory encoding after extensive left frontal LGG resection. In addition, it remains unknown whether these patients can improve their memory performance after instructions to apply efficient strategies. The neural correlates of verbal memory encoding were investigated in patients who had undergone extensive left frontal lobe (LFL) LGG resections and healthy controls using fMRI both before and after directed instructions were given for semantic organizational strategies. Participants were scanned during the encoding of word lists under three different conditions before and after a brief period of practice. The conditions included semantically unrelated (UR), related-non-structured (RNS), and related-structured words (RS), allowing for different levels of semantic organization. All participants improved on memory recall and semantic strategy application after the instructions for the RNS condition. Healthy subjects showed increased activation in the left inferior frontal gyrus (IFG) and middle frontal gyrus (MFG) during encoding for the RNS condition after the instructions. Patients with LFL excisions demonstrated increased activation in the right IFG for the RNS condition after instructions were given for the semantic strategies. Despite extensive damage in relevant areas that support verbal memory encoding and semantic strategy applications, patients that had undergone resections for LFL tumor could recruit the right-sided contralateral homologous areas after instructions were given and semantic strategies were practiced. These results provide insights into changes in brain activation areas typically implicated in verbal memory encoding and semantic processing.

Test-retest reliability of fMRI activation generated by different saccade tasks

PURPOSE

To assess the reproducibility of brain-activation and eye-movement patterns in a saccade paradigm when comparing subjects, tasks, and magnetic resonance (MR) systems.

MATERIALS AND METHODS

Forty-five healthy adults at two different sites (n = 45) performed saccade tasks with varying levels of target predictability: predictable (PRED), position predictable (pPRED), time predictable (tPRED), and prosaccade (SAC). Eye-movement pattern was tested with a repeated-measures analysis of variance. Activation maps reproducibility were estimated with the cluster overlap Jaccard index and signal variance coefficient of determination for within-subjects test-retest data, and for between-subjects data from the same and different sites.

RESULTS

In all groups latencies increased with decreasing target predictability: PRED < pPRED < tPRED < SAC (P < 0,001). Activation overlap was good to fair (>0.40) in all tasks in the within-subjects test-retest comparisons and poor (<0.40) in the tPRED for different subjects. The overlap of the different tasks for within-groups data was higher (0.40-0.68) than for the between-groups data (0.30-0.50). Activation consistency was 60-85% in the same subjects, 50-79% in different subjects, and 50-80% in different sites. In SAC, the activation found in the same and in different subjects was more consistent than in other tasks (50-80%).

CONCLUSION

The predictive saccade tasks produced evidence for brain-activation and eye-movement reproducibility.

Cortical thickness changes in the non-lesioned hemisphere associated with non-paretic arm immobilization in modified CI therapy

Recent evidence suggests that immobilization of the upper limb for 2–3 weeks induces changes in cortical thickness as well as motor performance. In constraint induced (CI) therapy, one of the most effective interventions for hemiplegia, the non-paretic arm is constrained to enforce the use of the paretic arm in the home setting. With the present study we aimed to explore whether non-paretic arm immobilization in CI therapy induces structural changes in the non-lesioned hemisphere, and how these changes are related to treatment benefit. 31 patients with chronic hemiparesis participated in CI therapy with (N = 14) and without (N = 17) constraint. Motor ability scores were acquired before and after treatment. Diffusion tensor imaging (DTI) data was obtained prior to treatment. Cortical thickness was measured with the Freesurfer software. In both groups cortical thickness in the contralesional primary somatosensory cortex increased and motor function improved with the intervention. However the cortical thickness change was not associated with the magnitude of motor function improvement. Moreover, the treatment effect and the cortical thickness change were not significantly different between the constraint and the non-constraint groups. There was no correlation between fractional anisotropy changes in the non-lesioned hemisphere and treatment outcome. CI therapy induced cortical thickness changes in contralesional sensorimotor regions, but this effect does not appear to be driven by the immobilization of the non-paretic arm, as indicated by the absence of differences between the constraint and the non-constraint groups. Our data does not suggest that the arm immobilization used in CI therapy is associated with noticeable cortical thinning.

Regulating Brownian fluctuations with tunable microscopic magnetic traps

A major challenge to achieving positional control of fluid borne submicron sized objects is regulating their Brownian fluctuations. We present a magnetic-field-based trap that regulates the thermal fluctuations of superparamagnetic beads in suspension. Local domain-wall fields originating from patterned magnetic wires, whose strength and profile are tuned by weak external fields, enable the bead trajectories within the trap to be managed and easily varied between strong confinements and delocalized spatial excursions that are described remarkably well by simulations.

First record of Aquanirmus major Cicchino & González Acuña (Phthiraptera: Philopteridae) on the Great Grebe, Podiceps major Boddaert (Aves: Podicipedidae) in Brazil

This report is the first record of a species of Aquanirmus in Brazil and it increases the known geographical distribution of A. major Cicchino & González Acuña, a species recently described based on material collected in Argentina and Chile.

Manipulation of magnetically labeled and unlabeled cells with mobile magnetic traps

A platform of discrete microscopic magnetic elements patterned on a surface offers dynamic control over the motion of fluid-borne cells by reprogramming the magnetization within the magnetic bits. T-lymphocyte cells tethered to magnetic microspheres and untethered leukemia cells are remotely manipulated and guided along desired trajectories on a silicon surface by directed forces with average speeds up to 20 microm/s. In addition to navigating cells, the microspheres can be operated from a distance to push biological and inert entities and act as local probes in fluidic environments.

Magnetic wire traps and programmable manipulation of biological cells

We present a multiplex method, based on microscopic programmable magnetic traps in zigzag wires patterned on a platform, to simultaneously apply directed forces on multiple fluid-borne cells or biologically inert magnetic microparticles or nanoparticles. The gentle tunable forces do not produce damage and retain cell viability. The technique is demonstrated with T-lymphocyte cells remotely manipulated (by a joystick) along desired trajectories on a silicon surface with average speeds up to 20 microm/s.

Anti-in?ammatory effect ofSolanum lycocarpum fruits

The croton oil-induced mouse ear oedema test, acetic acid-induced abdominal writhing, and carrageenan-induced peritonitis were used to study the anti-inflammatory effects of the crude ethanol extract and its alkaloid fraction from Solanum lycocarpum fruits. The alkaloid fraction induced a dose-dependent reduction in ear oedema formation and leukocyte migration, suggesting that S. lycocarpum fruits may contain steroidal alkaloids accounting for the anti-inflammatory effect of the crude ethanol extract.

Leaf gas exchange and carbohydrates in tropical trees differing in successional status in two light environments in central Amazonia

Monoculture and mixed stands of mahogany (Swietenia macrophylla King) and tonka bean (Dipteryx odorata Willd.) trees were established on degraded land in central Amazonia to compare leaf gas exchange parameters between plants grown in sunlight in an open field and in shade beneath a balsa wood (Ochroma pyramidale Cav.) canopy. Shading increased specific leaf area by about 50% in both species. Shading reduced height and diameter growth of S. macrophylla, whereas it increased these parameters for D. odorata. Light-saturated photosynthesis (Amax), stomatal conductance (gs) and transpiration (E) were higher in S. macrophylla than in D. odorata. In S. macrophylla, Amax was higher in sun leaves (12.9 +/- 0.9 micromol m-2 s-1) than in shade leaves (10.2 +/- 1.0 micromol m-2 s-1), whereas light environment had no significant effect on Amax of D. odorata. In both species, CO2-saturated photosynthesis (Apot) was higher in sun leaves (22 +/- 1.4 micromol m-2 s-1) than in shade leaves (17-20 +/- 0.8 micromol m-2 s-1). Stomatal conductance and E increased in sun leaves of S. macrophylla by 45 and 38%, respectively, whereas light environment did not affect gs and E of D. odorata. Photorespiration rates (Pr) varied from 28 to 36% of net photosynthesis (A) at ambient atmospheric CO2 concentration (Ca) but declined to around 7% of A at higher Ca. Leaf dark respiration (Rd) and the CO2 compensation point (Gamma) were lower in shade-grown plants than in open-grown plants. Compared with shade-grown plants, total nonstructural carbohydrate (TNC) concentrations increased by 56% in S. macrophylla and by 30% in D. odorata in the open field. Leaf nitrogen (NL) concentrations were higher in open-grown plants than in shade-grown plants of both species, and TNC and NL concentrations were negatively correlated (r = -0.77). High TNC accumulation in S. macrophylla in the open field suggests that photosynthesis is unlikely to be growth-limiting at this site. We conclude that photosynthetic parameters of D. odorata are less affected by light environment than those of S. macrophylla, indicating that D. odorata has lower physiological plasticity to light than S. macrophylla.

The N-terminal region of the Oenococcus oeni bacteriophage fOg44 lysin behaves as a bona fide signal peptide in Escherichia coli and as a cis-inhibitory element, preventing lytic activity on oenococcal cells

The function of the N-terminal region of the Oenococcus oeni phage fOg44 lysin (Lys44) as an export signal was investigated. We observed that when induced in Escherichia coli, Lys44 was cleaved between residues 27 and 28 in a SecA-dependent manner. Lys44 processing could be blocked by a specific signal peptidase inhibitor and was severely reduced by modification of the cleavage site. The lethal effect of Lys44 expression observed in E. coli was ascribed to the presence of its N-terminal 27-residue sequence, as its deletion resulted in the production of a nontoxic, albeit active, product. We have further established that lytic activity in oenococcal cells was dependent on Lys44 processing. An active protein with the molecular mass expected for the cleaved enzyme was detected in extracts from O. oeni-infected cells. The temporal pattern of its appearance suggests that synthesis and export of Lys44 in the infected host progress along with phage maturation. Overall, these results provide, for the first time, experimental evidence for the presence of a signal peptide in a bacteriophage lysin. Database searches and alignment of protein sequences support the prediction that other known O. oeni and Lactococcus lactis phages also encode secretory lysins. The evolutionary significance of a putative phage lysis mechanism relying on secretory lytic enzymes is tentatively discussed, on the basis of host cell wall structure and autolytic capacity.

[Application of the Portuguese version of the abbreviated instrument of quality life WHOQOL-bref]

INTRODUCTION

The need of short instruments to evaluate Quality of life determines World Health Organization Quality of Life Group (WHOQOL Group) to develop an abbreviated version of the WHOQOL-100, the WHOQOL-bref. The objective is to present the Brazilian field trial of the WHOQOL-bref.

METHODS

WHOQOL-bref is composed by 26 questions divided in four domains: physical, psychological, social relationships and environment. The evaliation instrument, BDI (beck depression inventory) and BHS (beck hopelessness scale) were used in a 300 subjects sample in Porto Alegre, South Brazil.

RESULTS/CONCLUSIONS

The instrument showed a good performance concerning internal consistency, discriminant validity, criterion validity, concurrent validity and test-retest reliability. The intrument allies good psychometric performance and practicity for use which puts it as an interesting option to evaluate quality of life in Brazil.

[Application of the Portuguese version of the instrument for the assessment of quality of life of the World Health Organization (WHOQOL-100)]

OBJECTIVE

The WHOQOL group have developed an instrument to evaluate Quality of Life, the WHOQOL-100, available in 20 different languages (WHOQOL Group, 1998). The field trial of the portuguese version of the instrument is presented.

METHODS

Two hundred and fifty patients from four main medical areas (Psychiatry, Clinical, Surgery and Ginecology) of the Hospital de Clínicas de Porto Alegre and 50 controls were evaluated with the Portuguese version of the WHO Quality of Life Instrument (WHOQOL-100), Beck Depression Inventory (BDI) and Beck Hopelessness Scale (BHS) in Porto Alegre, south Brazil.

RESULTS AND CONCLUSION

The instrument showed a good psychometric performance with good internal consistency, discriminant validity, criterion validity, concurrent validity and reliability. The authors conclude that the intrument is ready for use in Brazil, it being important to evaluate its performance in other regions and with different samples.

Gene organization in a central DNA fragment of Oenococcus oeni bacteriophage fOg44 encoding lytic, integrative and non-essential functions

The nucleotide sequence of a DNA fragment previously shown to contain the attachment site (attP) of Oenococcus oeni phage fOg44 (. Arch. Virol. 143, 523-536) has been determined. Sequence analysis indicated that this 6226bp EcoRI fragment harbours an integrase gene, in the vicinity of a direct repeat rich region defining attP, as well as genes encoding a muramidase-related lysin (Lys) and a holin polypeptide (Hol). Transcriptional studies suggested that lys and hol are mainly co-expressed, late in the lytic cycle, from a promotor located upstream of lys. Between the lytic cassette and the phage integration elements three additional open reading frames were found: orf217 and orf252 of unknown function and orf72, the putative product of which bears 32% identity with acidic excisionases from other Gram positive phages. We have established that the first two orfs, as well as the predicted promotor of orf72, are included in a 2143-bp DNA segment missing from the genome of the deletion mutant fOg44Delta2. Although lysogens of fOg44 and fOg44Delta2 exhibited similar properties, each phage produced two distinguishable types of lysogenic strains, differing in inducibility and immunity to other oenophages.

Genome diversity in temperate bacteriophages of Oenococcus oeni

The genome structure of six bacteriophages of Oenococcus oeni was compared. Two distinct groups with no apparent restriction site conservation were defined. In members of the alpha group (fOgML34, fOg4029, fOg30 and fOg218) a 7.5 kb region containing the origin of DNA packaging (cos) was highly conserved. Stretches of DNA heterogeneity could also be assigned to particular regions and were mostly evident in the right area of the genomes. fOg44 and fOgPSU1 (beta group) were indistinguishable in the left half of their genomes, including cos, but were markedly dissimilar in other regions. Strong labelling signals detected in cross-hybridizations involving members of different groups were confined to fragments centrally located in their physical maps. The attachment site (attP) of fOg44 was assigned to this conserved region. It is suggested that recombination events at this location may have been important in generating the observed diversity of oenophage genomes.

Nucleotide sequence analysis of pOg32, a cryptic plasmid from Leuconostoc oenos

Analysis of the nucleotide sequence of Leuconostoc oenos plasmid pOg32 (2544 bp) revealed three open reading frames (ORFs) in one of the DNA strands preceded by putative promoters and ribosome binding sites. ORF1 corresponded to a polypeptide similar to the replication proteins (Rep) of pT181 plasmid family. A nucleotide sequence like the double strand origin (DSO) of the same plasmid family was found inside the presumptive rep gene. ORF2 is capable of encoding a protein resembling the recombination enzyme (Pre) of two lactobacilli plasmids. Immediately upstream of the presumed pre gene, a sequence similar to the consensus RSA regions of those plasmids was encountered. Between ORF3 and ORF1, a sequence comparable to the RSB consensus region of the single strand origin ssoA was detected. The putative RSB region was located at the 3'-end of an imperfect palindrome which may be a single stranded origin. The described features, common to other small plasmids of Gram-positive bacteria, suggest that pOg32 replicates by the rolling circle mechanism. The amino acid sequence encoded by ORF3 was not similar to any known protein.

Inter-strain relationships among wine leuconostocs and their divergence from other Leuconostoc species, as revealed by low frequency restriction fragment analysis of genomic DNA

Thirty Leuconostoc oenos strains, representing 28 different isolates, were distributed into 20 genomic groups according to PFGE patterns of restriction digests. The 8 bp-specific enzymes Sfi I, Not I and Asc I cleaved the Leuc. oenos DNA in a mean of 17, 11 and four fragments respectively and Sma I produced more than 50 fragments per genome. The strain differentiating capacity of the four enzymes was similar; only two related genomic groups failed to be distinguished by Asc I or Not I. Genomic relationships between Leuc. oenos strains were quantified by numerical analysis of Not I and Sfi I banding patterns. More than half of the strains, including the starters ML34 and PSU-1, formed a major cluster. The average size of the Leuc. oenos genome was estimated as 1.86 Mb. Although similar values were obtained for the genomes of Leuc. mesenteroides, Leuc. pseudomesenteroides, Leuc. gelidum and Leuc. citreum, a significant divergence between wine and non-wine species was inferred from comparisons of genome cleavage frequencies, determined with five different enzymes.

Restriction analysis of PBS 1-related phages

The Bacillus subtilis bacteriophages AR 9, 3 NT, and I 10 belong to the same group as the widely used bacteriophage PBS 1. These four phages have in common, among other properties, flagellotropic adsorption to host cells and total substitution of thymine by uracil in their DNAs. We tested the action of different restriction endonucleases on the four genomes. Among 14 enzymes, which did cut the DNAs into discrete fragments, six are known as having at least one thymine residue in their recognition sequences. The electrophoretical patterns of the digested DNAs from the four phages show strong similarities. Nevertheless, the differences are sufficient to allow a clear distinction between them.

Phlebectasia within the sural nerve

During the period of one year, 222 patients were submitted to corrective surgery for varicose veins of the lower limbs; in 170 the short saphenous vein was removed. In ten of the latter patients there was phlebectasia of veins lying within the sural nerve. Intra-operative phlebography showed communicating veins between the area of phlebectasia and the deep venous system. These atypical communicating veins directed the venous flow toward the fibular and posterior tibial veins. The authors discuss the importance of these findings.