Multiple axonal tracing: simultaneous detection of three tracers in the same section

Multiple neuroanatomical tract-tracing methods are important tools for elucidating the connectivity between different populations of neurons. Evaluation of the question as to whether two specific fiber inputs converge on a particular, identified population of projection neurons requires the application of a triple-staining procedure that allows the unequivocal detection of three markers in a single section. The present report deals with a combination of tracing methods using anterogradely transported Phaseolus vulgaris leucoagglutinin and biotinylated dextran amine in conjunction with retrogradely transported Fluoro-Gold. These tracers were simultaneously detected according to a three-color paradigm, which includes the use of three different peroxidase substrates (nickel-enhanced diaminobenzidine, diaminobenzidine, and Vector VIP), thus resulting in three distinct precipitates: black, brown, and purple. We illustrate this method by showing convergence of projections arising from neurons located in two separate basal ganglia-related nuclei onto identified thalamostriatal projection neurons

Complex brain circuits studied via simultaneous and permanent detection of three transported neuroanatomical tracers in the same histological section.

Experimental neuroanatomical tracing methods lie at the basis of the study of the nervous system. When the scientific question is relatively straightforward, it may be sufficient to derive satisfactory answers from experiments in which a single neuroanatomical tracing method is applied. In various scientific paradigms however, for instance when the degree of convergence of two different projections on a particular cortical area or subcortical nucleus is the subject of study, the application of single tracing methods can be either insufficient or uneconomical to solve the questions asked. In cases where chains of projections are the subjects of study, the simultaneous application of two tracing methods or even more may be compulsory. The present contribution focuses on combinations of several neuroanatomical tract-tracing strategies, enabling in the end the simultaneous, unambiguous and permanent detection of three transported markers according to a three-color paradigm. A number of combinations of three tracers or of two tracers plus the immunocytochemical detection of a neuroactive substance can be conceived; we describe several of these combinations implemented by us using the present multitracer protocol

Analysis of event-related fmri data using diffusion maps

Abstract. The blood oxygen level-dependent (BOLD) signal in response to brief periods of stimulus can be detected using event-related functional magnetic resonance imaging (ER-fMRI). In this paper, we propose a new approach for the analysis of ER-fMRI data. We regard the time series as vectors in a high dimensional space (the dimension is the number of time samples). We believe that all activated times series share a common structure and all belong to a low dimensional manifold. On the other hand, we expect the background time series (after detrending) to form a cloud around the origin. We construct an embedding that reveals the organization of the data into an activated manifold and a cluster of non-activated time series. We use a graph partitioning technique–the normalized cut to find the separation between the activated manifold and the background time series. We have conducted several experiments with synthetic and in-vivo data that demonstrate the performance of our approach.

Mesquite pod extract modifies the reproductive physiology and behavior of the female rat

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Immunocompromised patients with acute respiratory distress syndrome : Secondary analysis of the LUNG SAFE database

The aim of this study was to describe data on epidemiology, ventilatory management, and outcome of acute respiratory distress syndrome (ARDS) in immunocompromised patients. Methods: We performed a post hoc analysis on the cohort of immunocompromised patients enrolled in the Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure (LUNG SAFE) study. The LUNG SAFE study was an international, prospective study including hypoxemic patients in 459 ICUs from 50 countries across 5 continents. Results: Of 2813 patients with ARDS, 584 (20.8%) were immunocompromised, 38.9% of whom had an unspecified cause. Pneumonia, nonpulmonary sepsis, and noncardiogenic shock were their most common risk factors for ARDS. Hospital mortality was higher in immunocompromised than in immunocompetent patients (52.4% vs 36.2%; p < 0.0001), despite similar severity of ARDS. Decisions regarding limiting life-sustaining measures were significantly more frequent in immunocompromised patients (27.1% vs 18.6%; p < 0.0001). Use of noninvasive ventilation (NIV) as first-line treatment was higher in immunocompromised patients (20.9% vs 15.9%; p = 0.0048), and immunodeficiency remained independently associated with the use of NIV after adjustment for confounders. Forty-eight percent of the patients treated with NIV were intubated, and their mortality was not different from that of the patients invasively ventilated ab initio. Conclusions: Immunosuppression is frequent in patients with ARDS, and infections are the main risk factors for ARDS in these immunocompromised patients. Their management differs from that of immunocompetent patients, particularly the greater use of NIV as first-line ventilation strategy. Compared with immunocompetent subjects, they have higher mortality regardless of ARDS severity as well as a higher frequency of limitation of life-sustaining measures. Nonetheless, nearly half of these patients survive to hospital discharge. Trial registration: ClinicalTrials.gov, NCT02010073. Registered on 12 December 2013