Low-dimensional organization of global brain states of reduced consciousness

Brain states are frequently represented using a unidimensional scale measuring the richness of subjective experience (level of consciousness). This description assumes a mapping between the high-dimensional space of whole-brain configurations and the trajectories of brain states associated with changes in consciousness, yet this mapping and its properties remain unclear. We combine whole-brain modeling, data augmentation, and deep learning for dimensionality reduction to determine a mapping representing states of consciousness in a low-dimensional space, where distances parallel similarities between states. An orderly trajectory from wakefulness to patients with brain injury is revealed in a latent space whose coordinates represent metrics related to functional modularity and structure-function coupling, increasing alongside loss of consciousness. Finally, we investigate the effects of model perturbations, providing geometrical interpretation for the stability and reversibility of states. We conclude that conscious awareness depends on functional patterns encoded as a low-dimensional trajectory within the vast space of brain configurations.

The impact of loneliness and social adaptation on depressive symptoms: Behavioral and brain measures evidence from a brain health perspective

Introduction

Early detection of depression is a cost-effective way to prevent adverse outcomes on brain physiology, cognition, and health. Here we propose that loneliness and social adaptation are key factors that can anticipate depressive symptoms.

Methods

We analyzed data from two separate samples to evaluate the associations between loneliness, social adaptation, depressive symptoms, and their neural correlates.

Results

For both samples, hierarchical regression models on self-reported data showed that loneliness and social adaptation have negative and positive effects on depressive symptoms. Moreover, social adaptation reduces the impact of loneliness on depressive symptoms. Structural connectivity analysis showed that depressive symptoms, loneliness, and social adaptation share a common neural substrate. Furthermore, functional connectivity analysis demonstrated that only social adaptation was associated with connectivity in parietal areas.

Discussion

Altogether, our results suggest that loneliness is a strong risk factor for depressive symptoms while social adaptation acts as a buffer against the ill effects of loneliness. At the neuroanatomical level, loneliness and depression may affect the integrity of white matter structures known to be associated to emotion dysregulation and cognitive impairment. On the other hand, socio-adaptive processes may protect against the harmful effects of loneliness and depression. Structural and functional correlates of social adaptation could indicate a protective role through long and short-term effects, respectively. These findings may aid approaches to preserve brain health via social participation and adaptive social behavior.

Biomarkers for dementia in Latin American countries: Gaps and opportunities

Limited knowledge on dementia biomarkers in Latin American and Caribbean (LAC) countries remains a serious barrier. Here, we reported a survey to explore the ongoing work, needs, interests, potential barriers, and opportunities for future studies related to biomarkers. The results show that neuroimaging is the most used biomarker (73%), followed by genetic studies (40%), peripheral fluids biomarkers (31%), and cerebrospinal fluid biomarkers (29%). Regarding barriers in LAC, lack of funding appears to undermine the implementation of biomarkers in clinical or research settings, followed by insufficient infrastructure and training. The survey revealed that despite the above barriers, the region holds a great potential to advance dementia biomarkers research. Considering the unique contributions that LAC could make to this growing field, we highlight the urgent need to expand biomarker research. These insights allowed us to propose an action plan that addresses the recommendations for a biomarker framework recently proposed by regional experts.

Abnormal Functional Hierarchies of EEG Networks in Familial and Sporadic Prodromal Alzheimer's Disease During Visual Short-Term Memory Binding

Alzheimer's Disease (AD) shows both complex alterations of functional dependencies between brain regions and a decreased ability to perform Visual Short-Term Memory Binding (VSTMB) tasks. Recent advances in network neuroscience toward understanding the complexity of hierarchical brain function here enables us to establish a link between these two phenomena. Here, we study data on two types of dementia at Mild Cognitive Impairment (MCI) stage-familial AD patients (E280A mutation of the presenilin-1 gene) and elderly MCI patients at high risk of sporadic AD, both with age-matched controls. We analyzed Electroencephalogram (EEG) signals recorded during the performance of Visual Short-Term Memory (VSTM) tasks by these participants. Functional connectivity was computed using the phase-lag index in Alpha and Beta; and network analysis was employed using network indices of hierarchical spread (degree variance) and complexity. Hierarchical characteristics of EEG functional connectivity networks revealed abnormal patterns in familial MCI VSTMB function and sporadic MCI VSTMB function. The middle-aged familial MCI binding network displayed a larger degree variance in lower Beta compared to healthy controls (p = 0.0051, Cohen's d = 1.0124), while the elderly sporadic MCI binding network displayed greater hierarchical complexity in Alpha (p = 0.0140, Cohen's d = 1.1627). Characteristics in healthy aging were not shown to differ. These results indicate that activity in MCI exhibits cross-frequency network reorganization characterized by increased heterogeneity of node roles in the functional hierarchy. Aging itself is not found to cause VSTM functional hierarchy differences.

Pilot study of an online intervention for young people with a first psychotic episode: Thinkapp

Introduction

Online interventions can be a complement to maintain the long-term effectiveness of psychosocial interventions in First Episode Psychosis (FEP) that have already demonstrated their efficacy in the short and medium term (Calvo et al., 2015).

Objectives

To test the effectiveness of a mobile app–based intervention (Thinkapp) to improve quality of life, functioning and symptomatology, and reduce days of admission and hospitalizations, in young people with FEP.

Methods

Fourteen patients with FEP, aged 14–30, recruited from Gregorio Marañón Hospital, Ramón y Cajal Hospital and AMAFE Foundation in Madrid (Spain) received treatment as usual plus a psychoeducational intervention through a mobile app. Changes in dependent variables over the course of the intervention were assessed by means of a battery of clinical tests at baseline, 3-month and 6-month follow-up using a Wilcoxon test.

Results

Of the fourteen patients included, 7 patients completed the 6-month follow-up and 8 completed the 3-month follow-up. There were significant differences in days of admission (p = 0.042) between baseline and 6-month follow-up. No significant results were observed in other clinical variables.

Conclusions

The study provides preliminary data potentially related to the reduction of days of admissions.

Disclosure

No significant relationships.

OP0215 WHAT DOES THE PATIENT WELL-BEING VAS TELL US WHEN THE PHYSICIAN GLOBAL ASSESSMENT SCORE IS ZERO? ANALYSIS OF A LARGE MULTINATIONAL DATASET

Background

Parent- and child-reported outcomes (PCROs) are measures that reflect the parent and child perception of rheumatic disease course and effectiveness of therapeutic interventions. Among PCROs for the assessment of patients with juvenile idiopathic arthritis (JIA), the most widely adopted is the parent/patient global evaluation or well-being visual analogue scale (WB-VAS). Several studies in JIA have highlighted the discrepancies in the assessment of the disease status between the physician and the parent/patient. This difference might be due to the WB-VAS measuring a broader construct than the physician global assessment (PGA).

Objectives

To evaluate, in a large multinational sample of JIA patients, the disease characteristics of subjects considered as inactive by the physician with an increased WB-VAS score.

Methods

Data from the multinational dataset of patients enrolled in the Epidemiology Treatment and Outcome of Childhood Arthritis (EPOCA) study were analyzed. We have included only subjects with a PGA score of 0. PCROs were collected through the juvenile arthritis multidimensional assessment report (JAMAR). We compared demographic features, socio-economic status, level of education, subtype of JIA diagnosis and the main PCROs (pain level, presence of morning stiffness, count of joints with swelling or pain, functional ability, disease activity level, ongoing therapy, presence of medications side effects and health related quality of life measured with the pediatric rheumatology quality of life (PRQL) scale) between subjects with WB-VAS ≤ 1 and > 1.

Results

A total of 3537 patients were sorted into two groups according to the WB_VAS score: 2862 subjects were included in a first group (WB_VAS ≤1); 675 in a second one (WB-VAS >1). Respectively, 17,6% and 18,1% of families belonged to the lower socio-economic status, 70,5% and 71% to the intermediate, 11,9% and 10,8% to the higher. The percentages of patients in the three levels of education was not different in the two groups:20,2% and 22% in the lower, 48,9% and 50,1% in the intermediate, 30,8% and 27,9% in the higher level of education. No significant difference was observed in the distribution of JIA categories in the two groups. Subjects in first group were younger at disease onset (5.6 vs 6.4 years). Comparison of main PCROs results is presented in the Table 1 below.

Table 1.PCROsWB_VAS ≤1WB_VAS >1pVAS_Pain (mean)0.3 (0.9)2.4 (2.4)<0.001Presence of morning stiffness (%)227 (8.0)285 (42.4)<0.001Patients under treatment (%)1919 (67.2)540 (80.2)<0.001Reporting side effects (%)421 (22.1)236 (43.9)<0.001Number of adverse events to the therapy (mean)0.2 (0.7)0.8 (1.5)<0.001Juvenile Arthritis Functionality Scale (JAFS)Total Score (mean)0.5 (1.6)3.0 (4.4)<0.001JIA Quality of Life (JQL) Total Score (mean)1.6 (2.3)6.4 (4.4)<0.001VAS-Disease Activity (mean)0.4 (1.3)2.3 (2.4)<0.001Count of active joints (mean)0.2 (0.7)1.4 (2.2)<0.001

Conclusion

We have analyzed the variables that might determine a difference between the physician’s assessment of inactive disease and the parent’s/patient’s perception of well-being. In particular, socio-economic status, level of education, and gender representation seem not to impact on the general perception of well-being, while pain seems to have the greatest influence on the parent/patient quality of life assessment. Finally, children with lower WB-VAS score were younger at disease onset.

References

[1]Consolaro A, et al. Phenotypic variability and disparities in treatment and outcomes of childhood arthritis throughout the world: an observational cohort study.Lancet Child Adolesc Health. 2019 Apr;3(4):255-263.

Disclosure of Interests

None declared

Effects of classic psychedelic drugs on turbulent signatures in brain dynamics

Psychedelic drugs show promise as safe and effective treatments for neuropsychiatric disorders, yet their mechanisms of action are not fully understood. A fundamental hypothesis is that psychedelics work by dose-dependently changing the functional hierarchy of brain dynamics, but it is unclear whether different psychedelics act similarly. Here, we investigated the changes in the brain’s functional hierarchy associated with two different psychedelics (LSD and psilocybin). Using a novel turbulence framework, we were able to determine the vorticity, i.e., the local level of synchronisation, which allowed us to extend the standard global time-based measure of metastability to become a local-based measure of both space and time. This framework produced detailed signatures of turbulence-based hierarchical change for each psychedelic drug, revealing consistent and discriminate effects on a higher-level network, i.e., the default mode network (DMN). Overall, our findings directly support a prior hypothesis that psychedelics modulate (i.e., ‘compress’) the functional hierarchy and provide a quantification of these changes for two different psychedelics. Implications for therapeutic applications of psychedelics are discussed.

Dementia with Lewy bodies research consortia: A global perspective from the ISTAART Lewy Body Dementias Professional Interest Area working group

Dementia with Lewy bodies (DLB) research has seen a significant growth in international collaboration over the last three decades. However, researchers face a challenge in identifying large and diverse samples capable of powering longitudinal studies and clinical trials. The DLB research community has begun to focus efforts on supporting the development and harmonization of consortia, while also continuing to forge networks within which data and findings can be shared. This article describes the current state of DLB research collaborations on each continent. We discuss several established DLB cohorts, many of whom have adopted a common framework, and identify emerging collaborative initiatives that hold the potential to expand DLB networks and diversify research cohorts. Our findings identify geographical areas into which the global DLB networks should seek to expand, and we propose strategies, such as the creation of data-sharing platforms and the harmonization of protocols, which may further potentiate international collaboration.

Perturbations in dynamical models of whole-brain activity dissociate between the level and stability of consciousness

Consciousness transiently fades away during deep sleep, more stably under anesthesia, and sometimes permanently due to brain injury. The development of an index to quantify the level of consciousness across these different states is regarded as a key problem both in basic and clinical neuroscience. We argue that this problem is ill-defined since such an index would not exhaust all the relevant information about a given state of consciousness. While the level of consciousness can be taken to describe the actual brain state, a complete characterization should also include its potential behavior against external perturbations. We developed and analyzed whole-brain computational models to show that the stability of conscious states provides information complementary to their similarity to conscious wakefulness. Our work leads to a novel methodological framework to sort out different brain states by their stability and reversibility, and illustrates its usefulness to dissociate between physiological (sleep), pathological (brain-injured patients), and pharmacologically-induced (anesthesia) loss of consciousness.

Using game authoring platforms to develop screen-based simulated functional assessments in persons with executive dysfunction following traumatic brain injury

The assessment of functional status is a critical component of clinical neuropsychological evaluations used for both diagnostic and therapeutic purposes in patients with cognitive brain disorders. There are, however, no widely adopted neuropsychological tests that are both ecologically valid and easily administered in daily clinical practice. This discrepancy is a roadblock to the widespread adoption of functional assessments. In this paper, we propose a novel approach using a serious game authoring platform (eAdventure) for creating screen-based simulated functional assessments. We created a naturalistic functional task that consisted of preparing a cup of tea (SBS-COT) and applied the assessment in a convenience sample of eight dyads of therapists/patients with mild executive dysfunction after traumatic brain injury. We had three main aims. First, we performed a comprehensive review of executive function assessment in activities of daily living. Second, we were interested in measuring the feasibility of this technology with respect to staffing, economic and technical requirements. Third, a serious game was administered to patients to study the feasibility of this technology in the clinical context (pre-screening test). In addition, quantitative (Technology Acceptance Model (TAM) questionnaires) and qualitative (semistructured interviews) evaluations were applied to obtain user input. Our results suggest that the staffing, economic and technical requirements of the SBS-COT are feasible. The outcomes of the pre-screening test provide evidence that this technology is useful in the functional assessment of patients with executive dysfunction. In relation to subjective data, the TAM questionnaire showed good user acceptability from a professional perspective. Interview analyses with professionals and patients showed positive experiences related to the use of the SBS-COT. Our work indicates that the use of these types of authoring platforms could have positive long-term implications for neuropsychological research, opening the door to more reproducible, cooperative and efficient research by allowing the facilitated production, reuse and sharing of neuropsychological assessment tools.

Behavioral Symptoms as Predictor Factor of Disease Progression Across Different Neurocognitive Disorders. A Longitudinal Study

Background

Previous works highlight the importance of neurocognitive symptoms over cognitive and functional dependency in neurocognitive disorders. However, little is known regarding to what extent presence of neuropsychiatric symptoms predicts disease progression, cognitive and functional impairments in behavioral variant frontotemporal dementia (bvFTD) and in Alzheimer dementia.

Methods

We performed two different evaluations (T1 and T2) with 3 years of difference in a group of bvFTD (n = 18), AD (n = 20) and controls (n = 22). Neuropsychological, clinical and cognitive correlates were measured in each time T1 and T2. By using different multiple regression models, we explored if behavioral symptoms (measured by Columbia, Yesavage at T1) predict disease progression as measured by changes over T1 and T2 in cognitive (MoCA, IFS, and clock figure) and functional dependency (Lawton).

Results

Behavioral symptoms, in particular depression, psychosis, apathy and disihinibition were factors able to predict cognitive and functional progression in bvFTD. By contrast, regression model revealed that depression and insomnia were behavioral factors able to predict progression in AD.

Conclusion

Neuropsychiatric symptoms are crucial to predict disease progression in bvFTD and AD patients in differentiated ways. Our results suggest tha tracking early behavioral symptoms in neurocognitive disorders playing an important role in the early detection, disease tracking, and neuroanatomical specification of bvFTD, as well as in future research on potential disease-modifying treatments.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

First Neuropsychiatric Symptoms and Neurocognitive Correlates of Behavioral Variant Frontotemporal Dementia

Previous works highlight the neurocognitive differences between apathetic and disinhibited clinical presentations of the behavioral variant frontotemporal dementia (bvFTD). However, little is known regarding how the early presentation (i.e., first symptom) is associated to the neurocognitive correlates of the disease's clinical presentation at future stages of disease. We analyzed the neurocognitive correlates of patients with bvFTD who debuted with apathy or disinhibition as first symptom of disease. We evaluated the neuropsychological, clinical and neuroanatomical (3 T structural images) correlates in a group of healthy controls (n = 30) and two groups of bvFTD patients (presented with apathy [AbvFTD, n = 18] or disinhibition [DbvFTD, n = 16]). To differentiate groups according to first symptoms, we used multivariate analyses. The first symptom in patients described the evolution of the disease. AbvFTD and DbvFTD patients showed increased brain atrophy and increased levels of disinhibition and apathy, respectively. Whole brain analyzes in AbvFTD revealed atrophy in the frontal, insular and temporal areas. DbvFTD, in turn, presented atrophy in the prefrontal regions, temporoparietal junction, insula and temporoparietal region. Increased atrophy in DbvFTD patients (compared to AbvFTD) was observed in frontotemporal regions. Multivariate analyses confirmed that a set of brain areas including right orbitofrontal, right dorsolateral prefrontal and left caudate were enough to distinguish the patients’ subgroups. First symptom in bvFTD patients described the neurocognitive impairments after around three years of disease, playing an important role in the early detection, disease tracking, and neuroanatomical specification of bvFTD, as well as in future research on potential disease-modifying treatments.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Decision-making interventions to stop the global atrial fibrillation-related stroke tsunami

Atrial fibrillation affects 33.5 million people worldwide and its prevalence is expected to double by 2050 because of the aging population. Atrial fibrillation confers a 5-fold higher risk of ischemic stroke compared to sinus rhythm. We present our view of the role of shared medical decision-making to combat global underutilization of oral anticoagulation for stroke prevention in atrial fibrillation patients. Oral anticoagulation underuse is widespread as it is present within atrial fibrillation patients of all risk strata and in countries across all income levels. Reasons for oral anticoagulation underuse include but are probably not limited to poor risk stratification, over-interpretation of contraindications, and discordance between physician prescription preferences and actual administration. By comparing a catastrophic event to the consequences of atrial fibrillation related strokes, it may help physicians and patients understand the negative outcomes associated with oral anticoagulation under-utilization and the magnitude to which oral anticoagulations neutralize atrial fibrillation burden.

Verbal Fluency as a Rapid Screening Test for Cognitive Impairment in Early Parkinson's Disease

The phonological verbal fluency test can act as a fast screening test to detect cognitive deficits in neurological conditions. In the present study, its utility in the detection of executive deficits in patients with early Parkinson's disease is demonstrated.

Contextual social cognition and the behavioral variant of frontotemporal dementia

The significance of social situations is commonly context-embedded. Although the role of context has been extensively studied in basic sensory processing or simple stimulus-response settings, its relevance for social cognition is unknown. We propose the social context network model (SCNM), a fronto-insular-temporal network responsible for processing social contextual effects. The SCNM may 1) update the context and use it to make predictions, 2) coordinate internal and external milieus, and 3) consolidate context-target associative learning. We suggest the behavioral variant of frontotemporal dementia (bvFTD) as a specific disorder in which the reported deficits in social cognition (e.g., facial recognition, empathy, decision-making, figurative language, theory of mind) can be described as context impairments due to deficits in the SCNM. Disruption of orbitofrontal-amygdala circuit, as well as the frontal, temporal, and insular atrophy in bVFTD, suggests a relationship between context-sensitive social cognition and SCNM. In considering context as an intrinsic part of social cognition, we highlight the need for a situated cognition approach in social cognition research as opposed to an abstract, universal, and decontextualized approach. The assessment of context-dependent social cognition paradigms, the SCNM, and their possible application to neuropsychiatric disorders may provide new insight into bvFTD and other related frontal disorders.

The relationship of clinical, cognitive and social measures in schizophrenia: a preliminary finding combining measures in probands and relatives

This study examines performance of schizophrenia patients, unaffected relatives and controls in social cognition, cognitive and psychiatric scales looking for possible markers of vulnerability in schizophrenia. Performance of schizophrenia patients from multiplex families, first-degree relatives, and matched controls was compared and, subsequently, discriminant analysis method was used for identifying the best predictors for group membership. By using Multigroup Discriminant Analyses on the three groups, the best predictors were PANSS, Premorbid Adjustment Scale, Faux Pas test, and a face/emotion categorizing task. This model obtained 82% correct global classification, suggesting that the combination of psychiatric scales and neuropsychological/social cognition tesks are the best approach for characterizing this disease. Although preliminary, our results suggest that social cognition tasks are robust markers of schizophrenia family impairments, and that combining clinical, social and neuropsychological measures is the best approach to asses patients and relatives vulnerability.

Association of mannose-binding lectin gene polymorphisms with antiphospholipid syndrome, cardiovascular disease and chronic damage in patients with systemic lupus erythematosus

OBJECTIVE

To investigate the association of mannose-binding lectin (MBL)-deficient genotypes with cardiovascular disease in a large series of patients with systemic lupus erythematosus (SLE).

METHODS

A total of 114 patients diagnosed with SLE were included in the study. MBL polymorphisms were investigated by sequencing-based DNA typing of the promoter and exon 1 of the MBL2 gene. The genotypes 0/0, 0/XA and XA/XA were considered as MBL-low genotypes.

RESULTS

A higher prevalence of cardiovascular disease was observed in patients carrying MBL-low genotypes compared with those carrying MBL-high genotypes [30 vs 9%, P = 0.012, odds ratio (OR) 4.54, 95% confidence interval (CI) 1.20-16.46]. Patients with MBL-low genotypes also presented higher mean values for total cholesterol (228.6 vs 202.3 mg/dl, P = 0.017) and low-density lipoprotein (LDL) cholesterol (139.9 vs 121.9 mg/dl, P = 0.045), a higher frequency of chronic renal failure (30 vs 4%, P = 0.001), vasculitis (30 vs 11%, P = 0.043), heart valve lesions (71 vs 32%, P = 0.026), cardiac valve dysfunction (57 vs 7%, P = 0.0004) and associated APS (39 vs 12%, P = 0.005), a higher mean Systemic Lupus International Collaborating Clinics score (2.09 vs 1.26, P = 0.029) and a lower prevalence of low C4 levels (43 vs 71%, P = 0.015). Multivariate analysis of genetic, clinical and immunological variables showed that only antiphospholipid syndrome (APS) was independently associated with cardiovascular events (P = 0.001).

CONCLUSION

Although the prevalence of cardiovascular disease in our SLE patients carrying MBL-deficient genotypes was 3.3 times higher than in patients with non-deficient genotypes, only APS was independently associated with cardiovascular events. This suggests that the higher frequency of thrombotic events in SLE patients carrying MBL-deficient genotypes might be related to coexisting APS.

Effect of the fluid in the inclusions of cement paste on the ultrasonic velocity

The durability of cement composites significantly depends on the movement of the fluids into the material through the porous system. The aqueous phase contained in the pores can cause irreversible damage from the dimensional stability viewpoint. In this sense, methods for non-destructive characterization of both, the porous structure and water content should be investigated. In this work, the effect of the fluid in the inclusions of the cement paste on the ultrasonic velocity is studied. Firstly, a theoretical analysis based on the micromechanical model, considering the microstructural information of the matrix and the fluid filling the pores, is presented. Some experimental work is made later using cement paste samples, whose porous structure is maintained dry or saturate with water. In both cases, the ultrasonic velocity is measured and compared to the one predicted by the micromechanical model. Using this technique, the ultrasonic velocity can be predicted with errors below 2% in the cases of dry or water saturated cement paste.

Worldwide Phylogeography of the Citrus Brown Spot Pathogen, Alternaria alternata

ABSTRACT Sixty-five isolates of Alternaria alternata were sampled from brown spot lesions on tangerines and mandarins (Citrus reticulata) and tangerine x grapefruit (C. reticulata x C. paradisi) hybrids in the United States, Colombia, Australia, Turkey, South Africa, and Israel to investigate the worldwide phylogeography of the fungus. Genetic variation was scored at 15 putative random amplified polymorphic DNA (RAPD) loci and 465 bp of an endo-polygalacturonase (endo-PG) gene was sequenced for each isolate. Cluster analysis of RAPD genotypes revealed significant differentiation between United State and Colombia isolates and Turkey, South Africa, Israel, and Australia isolates. Sequencing of endo-PG revealed 21 variable sites when the outgroup A. gaisen (AK-toxin-producing pathogen of Japanese pear) was included and 13 variable sites among the sampled isolates. Nucleotide substitutions at 10 of 13 variable sites represented silent mutations when endo-PG was translated in frame. Eight distinct endo-PG haplotypes were found among the sampled isolates and estimation of a phylogeny with endo-PG sequence data revealed three clades, each with strong bootstrap support. The most basal clade (clade 1) was inferred based on its similarity to the outgroup A. gaisen and consisted exclusively of pathogenic isolates from the United States and Colombia. Clade 2 consisted of pathogenic and nonpathogenic isolates from the United States, Australia, South Africa, and Israel and clade 3 contained pathogenic and nonpathogenic isolates from Australia, South Africa, Israel, and Turkey. Quantitative estimates of virulence (disease incidence) were obtained for isolates from the United States, Colombia, South Africa, Israel, and Turkey by spray inoculating detached citrus leaves and counting the number of lesions 24 h after inoculation. Large differences in virulence were detected among isolates within each location and isolates from the United States were significantly more virulent than isolates from other locations. Several isolates from Colombia, South Africa, Israel, and Turkey had low virulence and 8% of all isolates were nonpathogenic. All but one of the nonpathogenic isolates were found in clade 2 of the endo-PG phylogeny, which also included the most highly virulent isolates sampled.

Glucose biochip: dual analyte response in connection to two pre-column enzymatic reactions

This article describes a novel 'Lab-on-a-Chip' protocol generating two electrophoretic peaks for a single analyte, based on the coupling of two different pre-column enzymatic reactions of the same substrate followed by electrophoretic separation of the reaction products. Such operation is illustrated for the measurement of glucose in connection to the corresponding glucose oxidase (GOx) and glucose dehydrogenase (GDH) reactions. The pre-column enzymatic reactions generate hydrogen peroxide and NADH species, that are separated (based on their different charges) and detected at the end-column amperometric detector. The peak current ratio can be used for confirming the peak identity, estimating the peak purity, addressing co-migrating interferences, and deviations from linearity. A driving voltage of 2000 V results in peroxide and NADH migration times of 93 and 260 s, respectively. Factors influencing the unique dual glucose response are examined and optimized. The concept can be extended to different target analytes based on the coupling of two pre-column reactions with electrophoretic separation of the reaction products.

Cryptic 6q subtelomeric deletion associated with a paracentric inversion in a mildly retarded child

We report on a girl with minor anomalies and developmental delay carrying an apparently balanced paracentric inversion of chromosome 6q (q22qter). Fluorescent in situ hybridization analysis demonstrated a deletion of the subtelomeric region of 6q. This illustrates the use of specific subtelomeric fluorescent in situ hybridization probes to detect cryptic deletions as an important cause of mental retardation in seemingly balanced chromosome rearrangements.

Ser186Pro mutation of RHO gene in a Spanish autosomal dominant retinitis pigmentosa (ADRP) family

A Spanish family affected with autosomal dominant retinitis pigmentosa (ADRP) with a diffuse phenotype showed a mutation in the rhodopsin gene. The mutation was the transition T-->C in codon 186, which has been reported once before in an American patient (Dryja et al., Proc Natl Acad Sci USA 1991;88:9370-9374). This change replaces a serine by a proline in the second intradiscal loop of the protein, generating a molecule that is probably folding- and transport-defective.

Genetic Differentiation and Host Specificity Among Populations of Alternaria spp. Causing Brown Spot of Grapefruit and Tangerine x Grapefruit Hybrids in Florida

ABSTRACT Alternaria spp. were sampled from brown spot lesions in several geographically separated citrus groves and different grapefruit and tangerine x grapefruit hybrid cultivars in Florida and screened for variation at 16 putative random amplified polymorphic DNA loci. Populations of the pathogen on two hybrids, Minneola and Orlando, in five locations throughout Florida were moderately differentiated (Nei's coefficient of gene differentiation [G(ST)] = 0.12) among locations. The hypothesis that host-specialized forms of Alternaria spp. cause brown spot on different Citrus spp. and cultivars was tested by estimating genetic differentiation among isolates sampled from different hosts and by pathogenicity assays. Isolates sampled from grapefruit and the hybrid cv. Nova were genetically distinct from isolates sampled from other hybrid cultivars including Robinson, Sunburst, Minneola, Orlando, and Murcott. No differentiation could be detected among isolates sampled from this latter group of hybrids. Quantitative pathogenicity assays on leaves using spray inoculation revealed that 'Nova' isolates were not significantly more pathogenic on 'Nova' compared with isolates from 'Minneola' and 'Orlando'. Similarly, grapefruit isolates were not significantly more pathogenic on grapefruit compared with isolates from 'Minneola'. Isolates from all hosts had similar disease rankings on each inoculated cultivar, with 'Minneola' the most susceptible, followed in decreasing order of susceptibility by 'Orlando', 'Sunburst', 'Nova', and 'Duncan' grapefruit. Rough lemon was generally immune to all isolates tested; however, occasional brown spot lesions were observed on leaves of this host with isolates from grapefruit. No evidence was found to support the hypothesis that unique genotypes of the pathogen, which are more virulent on 'Sunburst' or grapefruit, have been introduced to Florida. Populations of Alternaria spp. causing brown spot of citrus on grapefruit and 'Nova' in Florida are genetically distinct from isolates on other cultivars, and we speculate that these populations are in the early stages of adaptation to and possible speciation on these hosts.

First mutation (S340X) in choroideremia gene in a Spanish family. Mutations in brief no. 173. Online

A study of choroideremia gene was performed in Spanish families affected with this disorder. One abnormal pattern was detected in exon eight corresponding to a new mutation not described before. The mutation was identified as a nonsense mutation S340X.

Pathological gambling and DNA polymorphic markers at MAO-A and MAO-B genes

This study was conducted to detect a possible association of MAOA and/or MAOB genes with pathological gambling (PG). DNA polymorphisms in MAOA and MAOB genes were screened by molecular analysis in 68 individuals (47 males and 21 females) meeting ICD-10 and DSM-IV criteria for pathological gambling and 68 healthy comparison controls matched for age and sex. There were no significant differences between pathological gamblers and healthy volunteers in overall allele distribution at the MAOA gene polymorphism. However there was a significant association between allele distribution and the subgroup of severe male gamblers (n = 31) compared to the males in the group of healthy volunteers (chi2 = 5246; df = 1; P < 0.05 [Bonferroni corrected]). No association was found between the MAOB polymorphic marker and PG. Allele variants at the MAOA, but not the MAOB gene may be a genetic liability factor in PG, at least in severe male gamblers. Molecular Psychiatry(2000) 5, 105-109.

Population Genetic Structure and Host Specificity of Alternaria spp. Causing Brown Spot of Minneola Tangelo and Rough Lemon in Florida

ABSTRACT Alternaria spp. were sampled from two rough lemon (RL) and two Minneola tangelo (MIN) groves in a limited geographic area in central Florida to test for host-specialized forms of the pathogen. Isolates of Alternaria spp. were scored for variation at 16 putative random amplified polymorphic DNA (RAPD) loci and for pathogenicity on both hosts. Subpopulations on each host were differentiated genetically and pathogenically, which was consistent with the hypothesis of host specialization. Highly significant genetic differentiation was detected among all four subpopulations (Nei's coefficient of gene differentiation [G(ST)] = 0.292, P = 0.000); most of the differentiation occurred between hosts (G(ST) = 0.278, P = 0.000). Phenograms of qualitative similarities among isolates within subpopulations revealed two or three distinct clusters of isolates within each subpopulation. The majority of isolates sampled from RL were pathogenic on RL and not on MIN, although a few RL isolates were able to induce disease on MIN, and 44% were nonpathogenic on either host. In contrast, isolates from MIN were pathogenic only on MIN, never on RL, and only 3% of the isolates were nonpathogenic. Overall, three genetically distinct clusters of isolates were detected on both hosts. One of the clusters (cluster A) sampled from RL was pathogenic on RL and not on MIN and consisted almost entirely of one RAPD genotype. This cluster also contained two isolates that were 93% similar to the majority genotype but were pathogenic on MIN and not RL. In isolates from MIN, two distinct clusters of isolates were found in one subpopulation (clusters B and C), and three distinct clusters were found in another subpopulation (clusters A, B, and C). Clusters A and B were found on both hosts, while cluster C was limited to MIN. Populations of Alternaria spp. sampled from RL and MIN showed a high degree of host specificity; however, the specificity obscured a high level of genetic variation within subpopulations.

Sleep disorders in bipolar depression: hypnotics vs sedative antidepressants

Ninety-six patients with bipolar disorder who attended a lithium clinic were reviewed in a retrospective study. Sleep disorders were studied in 85 depressive episodes. Eighty-one percent of the subjects presented with insomnia; the mixed type being the most frequent (49%) followed by early awakening (25%). The evolution of depression in the patients was compared according to the treatment received for insomnia: sedative antidepressants vs other anxiolytic or hypnotic drugs. Fifteen percent of patients shifted to mania, this group more frequently receiving sedative antidepressants (p < 0.05). Moreover, the patients who had received sedative antidepressants as therapy for insomnia (N = 61) showed a tendency to have a shorter asymptomatic interval before the following relapse (13 months vs 19 months; p = 0.06). In view of these results, we consider that the use of sedative antidepressants as a treatment for insomnia during depressive episodes in bipolar patients could be a factor contributing to worse prognoses; in these cases it appears that the use of other hypnotic drugs would be more advisable.

[Diastolic intraventricular gradient detected with Doppler echocardiography in hypertrophic cardiomyopathy. Report of a case]

It has recently been reported the rare existence of intraventricular diastolic gradients in patients with hypertrophic cardiomyopathy. This proves the great disturbance of diastolic function that exists in these patients. We report the case of a patient with this disease, in whom a significant diastolic intraventricular gradient was detected with color Doppler echocardiography. In the end we make a summing up of its most probable physiopathology.