Highly variable upper and abyssal overturning cells in the South Atlantic.

The Meridional Overturning Circulation (MOC) is a primary mechanism driving oceanic heat redistribution on Earth, thereby affecting Earth's climate and weather. However, the full-depth structure and variability of the MOC are still poorly understood, particularly in the South Atlantic. This study presents unique multiyear records of the oceanic volume transport of both the upper (<~3100 meters) and abyssal (>~3100 meters) overturning cells based on daily moored measurements in the South Atlantic at 34.5°S. The vertical structure of the time-mean flows is consistent with the limited historical observations. Both the upper and abyssal cells exhibit a high degree of variability relative to the temporal means at time scales, ranging from a few days to a few weeks. Observed variations in the abyssal flow appear to be largely independent of the flow in the overlying upper cell. No meaningful trends are detected in either cell.

High temperature aggravates the effects of pesticides in goldfish.

In human-altered rivers, fish are often conjointly exposed to an increase in water temperature due to global warming and to a contamination by organic pollutants such as pesticides, but their combined effects are still elusive. Thermal and chemical stressors could potentially interact because high temperature increases metabolism and toxicant uptake, and can alter the ability of organisms to set up adequate stress responses and to maintain homeostasis. These combined stressors could thus potentially result in higher level of molecular and cellular damage, and stronger effects on behavior and physiology, but experimental evidence across biological levels is still scarce. In this study, goldfish Carassius auratus were experimentally exposed to an environmentally realistic cocktail of pesticides (S-metolachlor, isoproturon, linuron, atrazine-desethyl, aclonifen, pendimethalin and tebuconazol) commonly found in rivers of South-West of France at low or high dose in two different thermal conditions: a common summer temperature (22 °C) or a high temperature recorded during heat waves (32 °C). Results showed that high temperature alone caused behavioral and physiological changes (increased swimming activity, increased hepatosomatic index, decreased reproductive index) but limited cellular damage. However, high temperature aggravated the effects of pesticides at the molecular and cellular level. Indeed, pesticide exposure resulted in higher genotoxic effects (micronuclei rate) and irreversible cellular damage of the gills and liver (apoptosis, inflammation, necrosis) at 32 °C compared to 22 °C. This suggests potential synergistic effects of climate change and pollution, and highlights the need for multiple stress approaches to better predict the impacts of human activities on aquatic wildlife.

Decision-making in a changing world: a study in autism spectrum disorders.

To learn to deal with the unexpected is essential to adaptation to a social, therefore often unpredictable environment. Fourteen adults with autism spectrum disorders (ASD) and 15 controls underwent a decision-making task aimed at investigating the influence of either a social or a non-social environment, and its interaction with either a stable (with constant probabilities) or an unstable (with changing probabilities) context on their performance. Participants with ASD presented with difficulties in accessing underlying statistical rules in an unstable context, a deficit especially enhanced in the social environment. These results point out that the difficulties people with ASD encounter in their social life might be caused by impaired social cues processing and by the unpredictability associated with the social world.

Quantification of Flavobacterium psychrophilum in rainbow trout, Oncorhynchus mykiss (Walbaum), tissues by qPCR.

A qPCR assay was developed for rapid and sensitive detection of Flavobacterium psychrophilum, the aetiological agent of bacterial cold-water disease and rainbow trout fry syndrome in salmonid fish worldwide. A set of F. psychrophilum-specific primers based on 16S rRNA gene sequences was designed and validated for specific detection and quantification of DNA isolated from representative strains of F. psychrophilum. The qPCR assay exhibited a high specificity for the 16S rRNA gene of F. psychrophilum (from 4 × 10(8) down to 11 copies per reaction) but not for other Flavobacterium species or other bacteria including fish pathogens. This qPCR-based method proved to be useful in the quantification of the F. psychrophilum titre present within organs dissected out from diseased fish. As the F. psychrophilum genome contains six copies of the 16S rRNA gene, we could infer a limit of detection corresponding to two bacteria per reaction, corresponding to 800 bacteria per fish tissue sample, and therefore 20 F. psychrophilum cells mg(-1) of tissue (for sample weighing 40 mg). The qPCR assay reported here could be a useful tool for veterinary diagnostic laboratories to monitor the F. psychrophilum infection level in fish farms.

Organic aerosol formation downwind from the Deepwater Horizon oil spill.

A large fraction of atmospheric aerosols are derived from organic compounds with various volatilities. A National Oceanic and Atmospheric Administration (NOAA) WP-3D research aircraft made airborne measurements of the gaseous and aerosol composition of air over the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico that occurred from April to August 2010. A narrow plume of hydrocarbons was observed downwind of DWH that is attributed to the evaporation of fresh oil on the sea surface. A much wider plume with high concentrations of organic aerosol (>25 micrograms per cubic meter) was attributed to the formation of secondary organic aerosol (SOA) from unmeasured, less volatile hydrocarbons that were emitted from a wider area around DWH. These observations provide direct and compelling evidence for the importance of formation of SOA from less volatile hydrocarbons.

[Pulmonary embolism: the extent of computerized tomography]. / Embolie pulmonaire : faut-il tendre vers le << tout angioscanner >> ?

The use of computerised tomography in the diagnosis of pulmonary embolism has been the subject of clinical research while, at the same time, technical progress has provided the current multidetector-row spiral equipment. Computerised tomography has been assessed both with respect to reference strategies as well as in extensive pragmatic trials. The preliminary evaluation of the clinical probability and the assay of d-dimers has progressively become imperative. The value of the venous doppler ultrasound of the legs, in particular in the elderly, is limited by the variable accessibility according to the centre. In rare cases, uncertainty persists, for example with a good quality negative multidetector-row spiral computerised tomography associated with a high clinical probability, leaving room for complementary explorations. The confrontation between clinicians and radiologists is then all the more pertinent.

The Flavobacterium psychrophilum OmpA, an outer membrane glycoprotein, induces a humoral response in rainbow trout.

AIMS: The purpose of this study was to characterize OmpA, a major glycoprotein isolated from the membrane fraction of Flavobacterium psychrophilum, and to evaluate its potential as antigenic unit in a possible vaccine. METHODS AND RESULTS: The expression product of ompA is a 465-amino-acid protein precursor that contains a 21-amino acid signal peptide and has overall homology (up to 60% identity) with similarly sized proteins of some bacteria belonging to the Flavobacteriaceae family. The carboxy-terminal region contains the 'OmpA/MotB' domain/signature and five putative 'Thrombospondin type 3 repeats' domains have been identified in the central region. OmpA was clearly detected in the outer membrane fraction and its surface exposure was demonstrated. OmpA is one of the immunodominant antigens and binding of specific anti-OmpA antibodies lead to cell lysis in the presence of complement. Fish immunized with OmpA emulsified with Freund's adjuvant developed a high antibody titter. CONCLUSIONS: Collectively, the data obtained here indicate that OmpA may be involved in Fl. psychrophilum/host cell interactions and appears to be a potential immunogen for a vaccine. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is one step in the direction of understanding pathogenesis of Fl. psychrophilum and development of future vaccine.

Impaired fronto-temporal processing of emotion in schizophrenia.

AIMS: Abnormal emotion processing in schizophrenia affects social and functional outcome. Spatiotemporal brain mechanisms underlying this deficit are unclear. MATERIALS AND METHODS: Event-related potential (ERP) responses to emotional and neutral face processing during an implicit (gender detection) and an explicit (expression detection) task were compared between a group of healthy volunteers (n=10) and a group of patients with schizophrenia (n=10). RESULTS: Whereas patients had normal primary visual cortex responses, the early modulation of occipital, temporal, and frontal responses by emotional expression observed in controls was absent in patients. The occipito-temporal N170 amplitude was reduced in patients relative to controls during expression detection, but not during gender detection. Frontal activity within 180-250ms was reduced in patients compared to controls. As opposed to controls, no significant difference was seen in patients at the right temporal electrode (T6) between amplitudes of long-latency ERPs elicited by distinct emotions during the expression detection task. CONCLUSION: In patients with schizophrenia, abnormal early extraction of expression-related information in the occipito-temporal cortex (before 170ms) impairs structural encoding of facial expressions (N170) and may disrupt motivation- and task-dependent context processing (180-250ms time window) of expression-related facial features. Moreover, top-down neuromodulation from frontal and limbic structures to visual occipito-temporal cortex may not be sufficient to optimize the extraction of expression-specific face features.

[Part I: Face recognition]. / Les visages et leurs émotions.

Faces represent a crucial vector of interhuman communication. The message transmitted by the face has multiple features. Recognition of each feature can be impaired independently or in combination with others. In order to understand the behavioral consequences of such impairments, which can be a major social handicap, we first must specify the neural networks involved in face recognition. We propose in this first part to present the systems involved in face recognition, in particular the question of identity and prosopagnosia. Different neural networks are indeed implicated in the recognition of invariant facial features such as identity, gender, ethnicity, and recognition of variant features like facial expression and eye gaze. This paper is illustrated by some of our scalp and intracranial electrophysiological studies performed in humans allowing us to describe some aspects of face recognition dynamics combining an excellent spatial and temporal resolution. Intracranial recordings were performed in drug refractory epileptical patients implanted with depth electrodes. These studies demonstrate that numerous deep brain and cortical structures participate early and sometimes in a sustained manner in face recognition.

[Part II: Recognising facial expressions]. / Les visages et leurs émotions.

In this second part, we address particularly the question of the neural mechanisms and structures involved in the recognition of facial emotional expressions that are crucial in social cognition. Emotion recognition in others can be critically impaired in some neurodegenerative and neurovascular diseases. That dysfunction sometimes correlated to disabling behavioural disorders and interpersonal communication impairment must be further understood. The results of a series of scalp and intracranial event related potential recordings, as well as recent advances in the literature, are reported. ERPs to facial emotional expressions were thus recorded in multiple subcortical and cortical areas in drug refractory epileptical patients implanted with depth electrodes. The roles of amygdala, insula and prefrontal cortex located at crossroads between perceptive analysis and emotional conceptual knowledge are particularly underlined. Altogether, these studies demonstrate that facial expressions are widely processed in space and time, some structures reacting very early and automatically, others providing a sustained reaction depending on the attention.

Identification of P18, a surface protein produced by the fish pathogen Flavobacterium psychrophilum.

AIMS: This study was focused on the identification of associated outer membrane proteins which may play a role in the specific interactions between Flavobacterium psychrophilum (the aetiological agent of cold-water disease and rainbow trout fry syndrome in salmonid fish worldwide) and the fish tissues. METHODS AND RESULTS: The surface protein interactions with the outer membrane being mainly ionic, different methods were used for the detachment of proteins from the cell surface of Fl. psychrophilum involving detergent-free buffers or solutions known to perturb the ionic interactions. Such treatments led to the isolation of a surface protein, named P18 in accordance with its relative molecular mass. The expression of P18 was not related to the growth conditions (liquid or solid medium, temperature and aeration) or the strains of Fl. psychrophilum tested here. CONCLUSIONS: Preliminary characterization indicated that P18 is a surface antigen which is not sugar-modified and might be a subunit of a surface layer (i.e. S-layer), one of the most common surface structures on bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Data reported here should be used as the basis for further works involving the purification and characterization of P18 to identify the specific roles of such a surface protein, especially the interaction between this protein and the host surface.

Factors associated with efavirenz discontinuation in a large community-based sample of patients.

Efavirenz (EFV) is a potent antiretroviral drug; its use may be limited, however, by psychiatric symptoms that require its discontinuation. We sought to identify the characteristics that placed patients at an elevated risk of discontinuation. Data for this cross-sectional study came from a self-administered questionnaire distributed by French AIDS community associations; it collected information about sociodemographic characteristics, addictive behaviours, treatment regimens, EFV history and depression. Patients remaining on EFV for more than six months were compared with those who stopped taking it. Of the 828 patients who completed the questionnaire, 175 had taken EFV for at least six months, and 152 had discontinued it (median months [IQR] of exposure=4[2-10]). Of these 327 patients (median age=42), 23% were women, 46% were unemployed, 38% had a steady sexual partner and 24% reported a history of multiple depressive episodes. Logistic regression showed that the factors independently associated with EFV discontinuation were female gender (OR[95%CI]=2.2[1.2-3.8]), unemployment (1.8[1.1-2.8]), a steady sexual partner (1.7[1-2.5]) and multiple episodes of depression (2.6[1.5-4.5]). Clinicians should keep in mind the neuropsychiatric risks of EFV during the first year, especially among patients with a history of multiple depressive episodes.

Purification and characterization of a membrane glycoprotein from the fish pathogen Flavobacterium psychrophilum.

AIMS: The cell envelope of the fish pathogen Flavobacterium psychrophilum contains more than 50 polypeptides resolved by sodium dodecyl sulphate-polyacrylaminde gel electrophoresis analysis including a major component named P60. Here, we have developed a simple and efficient procedure for the purification of P60 and therefore permitting its biochemical characterization. METHODS AND RESULTS: Membrane proteins were selectively extracted from isolated cell envelopes with the mild non-ionic detergent Triton X-100. About 10 polypeptides were identified from the detergent fraction, including P60. The P60-enriched fraction was thereafter subjected to an anion exchange chromatographic step in the presence of Triton X-100. The molecule was purified at the milligram level (yield, about 75%; purification factor, 6.2). Analyses performed by charge shift electrophoresis, Triton X-114 phase separation and by detection of sugar-modified components showed that P60 is a true amphiphilic membrane-associated glycoprotein. CONCLUSIONS: The method described in this paper provides pure and non-denaturated P60 and should prove to be easily scaled-up. As sugar-modified protein, P60 should be included in the growing list of glycosylated prokaryotic proteins. SIGNIFICANCE AND IMPACT OF THE STUDY: It offers the possibility of obtaining P60 in amounts allowing the testing of the potential of P60 as a candidate for anti-flavobacteria subunit vaccines, as P60 is one of the major antigens.

Chemical analysis of lipid-modified membrane proteins in Acholeplasma laidlawii.

The lipid modification of membrane proteins was investigated in Acholeplasma laidlawii by metabolic labeling and by chemical analysis. A S-glycerylcysteine residue was identified from membrane proteins and we reported the strong preference for saturated acyl chains into the lipid modification. Differential release of fatty acids revealed a ratio [(O-ester- + amide-bound acyl chains)/O-ester-linked chains] close to 1.1 which suggests the involvement of only two O-ester linked fatty acids in the acylation process. Present data indicate that acyl proteins in A. laidlawii are true lipoproteins (mainly diacylated) probably processed by a mechanism analogous to that described for eubacteria and other mycoplasmas.

Adult cardiac myocytes survive and remain excitable during long-term culture on synthetic supports.

OBJECTIVE: Cardiomyocytes can be transplanted successfully into skeletal and cardiac muscle. Our goal was to determine the feasibility of grafting cardiomyocytes onto various synthetic supports to create an excitable and viable tissue for implantation. METHODS: Adult rat cardiomyocytes were cultured over an 8-week period onto different substitutes, including human glutaraldehyde-treated pericardium (n = 3), equine glutaraldehyde-treated pericardium (n = 3), polytetrafluoroethylene (n = 8), Dacron polyester (n = 16), and Vicryl polyglactin (n = 8). RESULTS: Only the cells seeded on the Dacron survived, with the synthetic fibers colonized at 8 weeks. On the other supports, the number of myocytes progressively decreased from the first week, with their density (number of cells per square millimeter) being, after 20 days, 17 +/- 2 on the polytetrafluoroethylene and 5 +/- 1 on the human or equine pericardium compared with 45 +/- 3 on the Dacron. After 8 weeks of culture on Dacron, the sarcomeric protein (sarcomeric alpha-actinin) was detected in all cells. In addition, the staining was regularly arranged and well aligned in a striated pattern. Spontaneous beating activity was obtained. Moreover, electrical stimulation of the cell preparation resulted in the generation of calcium transients, the frequency of which followed the frequency of the electrical stimulation. CONCLUSIONS: These results suggest that adult cardiac myocytes remain viable and excitable during long-term culture on a 3-dimensional Dacron support, which might constitute a new synthetic cardiac tissue.

Biochemical and antigenic characterisation of Mycoplasma gallisepticum membrane proteins P52 and P67 (pMGA).

Two membrane proteins from the avian pathogen Mycoplasma gallisepticum have been previously purified using a simple, efficient and non-denaturing method: a lipoprotein P67 (pMGA) and P52. In the current study, the lipid part of P67 was chemically analysed. The molecular structure of the lipoprotein-lipid component was determined to be S-glyceryl cysteine with two O-ester-linked acyl chains. Fatty acid analysis of the purified P67 indicated a heterogeneous composition: palmitic acid (16:0)>stearic acid (18:0)>oleic acid (18:1c)>myristic acid (14:0), with 16:0 as the major component. These findings, along with previously published results, support the conclusion that P67 is pMGA1.2, a true membrane-associated lipoprotein although not N-acylated. In contrast to P67, P52 is not a lipoprotein. Topological experiments using in situ treatment with proteases and growth inhibition in the presence of anti-P52 serum provided evidence of the surface exposition of the polypeptide. The N-terminal sequence of P52 was found to be similar to the dihydrolipoamide acetyltransferase from several mollicutes; this enzyme is a membrane-associated component of the pyruvate dehydrogenase complex. Immunoblotting techniques revealed that the surface antigens P52 and P67 were specific to the species M. gallisepticum and the closely related species M. imitans. No antigenic difference was revealed within these species with the anti-P52 serum, while anti-P67 serum confirmed the antigenic variability of P67. The potential of P52 and P67 as antigens in serological diagnosis tests or as candidates for anti-mycoplasma subunit vaccines is discussed.

Unilateral right parietal damage leads to bilateral deficit for high-level motion.

Patients with right parietal damage demonstrate a variety of attentional deficits in their left visual field contralateral to their lesion. We now report that patients with right lesions also show a severe loss in the perception of apparent motion in their "good" right visual field ipsilateral to their lesion. Three tests of attention were conducted, and losses were found only in the contralesional fields for a selective attention and a multiple object tracking task. Losses in apparent motion, however, were bilateral in all cases. The deficit in apparent motion in the parietal patients supports previous claims that this relatively effortless percept is mediated by attention. However, the bilateral deficit suggests that the disruption is due to a bilateral loss in the temporal resolution of attention to transient events that drive the apparent motion percept.

Low catecholamine concentrations protect adult rat ventricular myocytes against apoptosis through cAMP-dependent extracellular signal-regulated kinase activation.

Catecholamines have complex effects on cardiac myocyte growth and survival, including the triggering of apoptosis at high concentration. Here, we examined whether at a lower concentration, catecholamine protected adult rat ventricular myocytes from apoptosis in vitro. Myocytes were exposed to staurosporine (ST, 10 microM) for 18 h, with or without epinephrine (0.1 or 10 microM) or fetal calf serum (10%). Apoptosis was assessed after 48 h of culture in terms of DNA fragmentation (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling method, DNA gel electrophoresis). Epinephrine (0.1 microM) and serum reduced ST-induced myocyte apoptosis by approximately 50% (n = 12 cultures, P <.001), whereas epinephrine and serum alone did not influence the low apoptotic rate in control cultures. In contrast, 10 microM epinephrine induced marked apoptosis in ST-free conditions. The protective effects of 0.1 microM epinephrine and serum were blunted by the tyrosine kinase inhibitor genistein (n = 12 cultures, P <. 001). Extracellular signal-regulated kinase (ERK) activity was stimulated by 0.1 microM epinephrine but not by 10 microM epinephrine. Furthermore, the protective effect of epinephrine was mimicked by isoproterenol (1 microM) and forskolin (1 microM) but not by phenylephrine (10 microM) and was blunted by propranolol (10 microM) but not by prazozin (10 microM). Finally, isoproterenol and forskolin activated ERK, an effect that was blunted by propranolol. In conclusion, low epinephrine concentrations attenuate ST-induced apoptosis of adult cardiac myocytes in vitro, an effect mediated by coupling between the cAMP pathway and ERK activation. This suggests that a minimal adrenergic tone is essential for myocyte survival in conditions of unusual stress.

Able to name, unable to compare: the visual abilities of a posterior split-brain patient.

A patient with a lesion of the posterior half of the corpus callosum correctly named simple (e.g. colors) and complex (e.g. faces) stimuli whether presented to one or both hemifields. Although proficient at these tasks, and also able to make same/different judgements for stimuli within an hemifield, he failed dramatically when required to compare stimuli between the two hemifields. These results indicate that, while the posterior portion of the corpus callosum may not be essential for naming visual stimuli, it is essential for comparing stimuli between the two visual fields.