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12
result(s) for
"Laffont, Benoit"
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Platelet microparticles are internalized in neutrophils via the concerted activity of 12-lipoxygenase and secreted phospholipase A₂-IIA
by
Laffont, Benoit
,
Tremblay, Jacques J.
,
Duchez, Anne-Claire
in
12-Hydroxy-5,8,10,14-eicosatetraenoic Acid - metabolism
,
Animals
,
Arachidonate 12-Lipoxygenase - genetics
2015
Platelets are anucleated blood elements highly potent at generating extracellular vesicles (EVs) called microparticles (MPs). Whereas EVs are accepted as an important means of intercellular communication, the mechanisms underlying platelet MP internalization in recipient cells are poorly understood. Our lipidomic analyses identified 12(S)-hydroxyeicosatetranoic acid [12(S)-HETE] as the predominant eicosanoid generated by MPs. Mechanistically, 12(S)-HETE is produced through the concerted activity of secreted phospholipase A₂ IIA (sPLA₂-IIA), present in inflammatory fluids, and platelet-type 12-lipoxygenase (12-LO), expressed by platelet MPs. Platelet MPs convey an elaborate set of transcription factors and nucleic acids, and contain mitochondria. We observed that MPs and their cargo are internalized by activated neutrophils in the endomembrane system via 12(S)-HETE. Platelet MPs are found inside neutrophils isolated from the joints of arthritic patients, and are found in neutrophils only in the presence of sPLA₂-IIA and 12-LO in an in vivo model of autoimmune inflammatory arthritis. Using a combination of genetically modified mice, we show that the coordinated action of sPLA₂-IIA and 12-LO promotes inflammatory arthritis. These findings identify 12(S)-HETE as a trigger of platelet MP internalization by neutrophils, a mechanism highly relevant to inflammatory processes. Because sPLA₂-IIA is induced during inflammation, and 12-LO expression is restricted mainly to platelets, these observations demonstrate that platelet MPs promote their internalization in recipient cells through highly regulated mechanisms.
Journal Article
An Expanded Landscape of Unusually Short RNAs in 11 Samples from Six Eukaryotic Organisms
2022
Small RNA sequencing (sRNA-Seq) approaches unveiled sequences derived from longer non-coding RNAs, such as transfer RNA (tRNA) and ribosomal RNA (rRNA) fragments, known as tRFs and rRFs, respectively. However, rRNAs and RNAs shorter than 16 nt are often depleted from library preparations/sequencing analyses, although they may be functional. Here, we sought to obtain a complete repertoire of small RNAs by sequencing the total RNA from 11 samples of 6 different eukaryotic organisms, from yeasts to human, in an extended 8- to 30-nt window of RNA length. The 8- to 15-nt window essentially contained fragments of longer non-coding RNAs, such as microRNAs, PIWI-associated RNAs (piRNAs), small nucleolar RNAs (snoRNAs), tRNAs and rRNAs. Notably, unusually short RNAs < 16 nt were more abundant than those >16 nt in bilaterian organisms. A new RT-qPCR method confirmed that two unusually short rRFs of 12 and 13 nt were more overly abundant (~3-log difference) than two microRNAs. We propose to not deplete rRNA and to reduce the lower threshold of RNA length to include unusually short RNAs in sRNA-Seq analyses and datasets, as their abundance and diversity support their potential role and importance as biomarkers of disease and/or mediators of cellular function.
Journal Article
Microvascular decompression of cochlear nerve for tinnitus incapacity: pre-surgical data, surgical analyses and long-term follow-up of 15 patients
2008
The level of success of neurovascular decompression in ponto-cerebellar angle for hemifacial spasm and trigeminal neuralgia has already established the reality of the pathology to explain such symptoms. However, cochlear nerve compression syndrome by vascular loop is still a controversial topic. We have performed a retrospective cases review with long-term follow-up (5–7 years) concerning the results of microvascular decompression surgery of the cochlear nerve via an endoscopy assisted retrosigmoid approach on 15 patients suffering from unilateral incapacitating tinnitus with abnormal auditory brainstem response and an offending vessel on magnetic resonance imaging. During the surgery, a vascular compression was found on every patient. In a long-term follow-up, 53.3% (8 cases) of our tinnitus cases improved and 20% (3 cases) of them were completely cured. The ABR returned to normal in all patients who had good clinical results (diminished or disappeared tinnitus). When a vertebral artery loop (5 cases) was concerned we obtained 80% of good clinical results. No one showed amelioration or sudden aggravation of their hearing. Three cases required surgical correction of cerebrospinal fluid leak and one case developed spontaneously regressive swallowing problems. Such microvascular decompression surgery of the cochlear nerve appears to be successful in treating incapaciting tinnitus in particular when a vertebral artery loop is observed. Therefore, in such a case, one might recommend neurovascular decompression surgery, keeping in mind that the complications of this surgery should be minimized by a careful closure of the retrosigmoid approach. In order to ensure a better selection of patient more accurate cochlear nerve monitoring and functional MRI should be a promising assessment.
Journal Article
Altered microRNA Transcriptome in Cultured Human Liver Cells upon Infection with Ebola Virus
by
Laugier, Jonathan
,
Kozak, Robert
,
Laffont, Benoit
in
Cell Line, Tumor
,
Cytokine storm
,
Ebola virus
2021
Ebola virus (EBOV) is a virulent pathogen, notorious for inducing life-threatening hemorrhagic fever, that has been responsible for several outbreaks in Africa and remains a public health threat. Yet, its pathogenesis is still not completely understood. Although there have been numerous studies on host transcriptional response to EBOV, with an emphasis on the clinical features, the impact of EBOV infection on post-transcriptional regulatory elements, such as microRNAs (miRNAs), remains largely unexplored. MiRNAs are involved in inflammation and immunity and are believed to be important modulators of the host response to viral infection. Here, we have used small RNA sequencing (sRNA-Seq), qPCR and functional analyses to obtain the first comparative miRNA transcriptome (miRNome) of a human liver cell line (Huh7) infected with one of the following three EBOV strains: Mayinga (responsible for the first Zaire outbreak in 1976), Makona (responsible for the West Africa outbreak in 2013–2016) and the epizootic Reston (presumably innocuous to humans). Our results highlight specific miRNA-based immunity pathways and substantial differences between the strains beyond their clinical manifestation and pathogenicity. These analyses shed new light into the molecular signature of liver cells upon EBOV infection and reveal new insights into miRNA-based virus attack and host defense strategy.
Journal Article
Platelet microparticles are internalized in neutrophils via the concerted activity of 12-lipoxygenase and secreted phospholipase A 2 -IIA
2015
On activation, blood platelets package components from their cytoplasm into microparticles (MPs), tiny vesicles released by cytoplasmic membrane budding and shedding. Given that MPs can impact other cellular lineages on internalization, we aimed to decipher the mechanisms promoting MP internalization by cellular recipients. We modeled MP internalization by neutrophils and identified a predominant lipid, 12(S)-hydroxyeicosatetranoic acid, as a mediator critical for the promotion of MP internalization. MPs were found inside neutrophils from individuals with rheumatoid arthritis, and their presence in neutrophils in the joints of mice treated with arthritogenic serum is dependent on the expression of enzymes implicated in the generation of 12(S)-hydroxyeicosatetranoic acid. These findings reveal a unique molecular mechanism implicated in MP internalization relevant to inflammatory processes. Platelets are anucleated blood elements highly potent at generating extracellular vesicles (EVs) called microparticles (MPs). Whereas EVs are accepted as an important means of intercellular communication, the mechanisms underlying platelet MP internalization in recipient cells are poorly understood. Our lipidomic analyses identified 12(S)-hydroxyeicosatetranoic acid [12(S)-HETE] as the predominant eicosanoid generated by MPs. Mechanistically, 12(S)-HETE is produced through the concerted activity of secreted phospholipase A 2 IIA (sPLA 2 -IIA), present in inflammatory fluids, and platelet-type 12-lipoxygenase (12-LO), expressed by platelet MPs. Platelet MPs convey an elaborate set of transcription factors and nucleic acids, and contain mitochondria. We observed that MPs and their cargo are internalized by activated neutrophils in the endomembrane system via 12(S)-HETE. Platelet MPs are found inside neutrophils isolated from the joints of arthritic patients, and are found in neutrophils only in the presence of sPLA 2 -IIA and 12-LO in an in vivo model of autoimmune inflammatory arthritis. Using a combination of genetically modified mice, we show that the coordinated action of sPLA 2 -IIA and 12-LO promotes inflammatory arthritis. These findings identify 12(S)-HETE as a trigger of platelet MP internalization by neutrophils, a mechanism highly relevant to inflammatory processes. Because sPLA 2 -IIA is induced during inflammation, and 12-LO expression is restricted mainly to platelets, these observations demonstrate that platelet MPs promote their internalization in recipient cells through highly regulated mechanisms.
Journal Article
Platelet microparticles are internalized in neutrophils via the concerted activity of 12-lipoxygenase and secreted phospholipase A^sub 2^-IIA
by
Laffont, Benoit
,
Duchez, Anne-Claire
,
Soulet, Denis
in
Arthritis
,
Blood platelets
,
Cellular biology
2015
Platelets are anucleated blood elements highly potent at generating extracellular vesicles (EVs) called microparticles (MPs). Whereas EVs are accepted as an important means of intercellular communication, the mechanisms underlying platelet MP internalization in recipient cells are poorly understood. Our lipidomic analyses identified 12(S)-hydroxyeicosatetranoic acid [12(S)-HETE] as the predominant eicosanoid generated by MPs. Mechanistically, 12(S)-HETE is produced through the concerted activity of secreted phospholipase A2 IIA (sPLA2-IIA), present in inflammatory fluids, and platelet-type 12-lipoxygenase (12-LO), expressed by platelet MPs. Platelet MPs convey an elaborate set of transcription factors and nucleic acids, and contain mitochondria. We observed that MPs and their cargo are internalized by activated neutrophils in the endomembrane system via 12(S)-HETE. Platelet MPs are found inside neutrophils isolated from the joints of arthritic patients, and are found in neutrophils only in the presence of sPLA2-IIA and 12-LO in an in vivo model of autoimmune inflammatory arthritis. Using a combination of genetically modified mice, we show that the coordinated action of sPLA2-IIA and 12-LO promotes inflammatory arthritis. These findings identify 12(S)-HETE as a trigger of platelet MP internalization by neutrophils, a mechanism highly relevant to inflammatory processes. Because sPLA2-IIA is induced during inflammation, and 12-LO expression is restricted mainly to platelets, these observations demonstrate that platelet MPs promote their internalization in recipient cells through highly regulated mechanisms.
Journal Article
Platelet microparticles are internalized in neutrophils via the concerted activity of 12-lipoxygenase and secreted phospholipase A sub( 2)-IIA
2015
Platelets are anucleated blood elements highly potent at generating extracellular vesicles (EVs) called microparticles (MPs). Whereas EVs are accepted as an important means of intercellular communication, the mechanisms underlying platelet MP internalization in recipient cells are poorly understood. Our lipidomic analyses identified 12(S)-hydroxyeicosatetranoic acid [12(S)-HETE] as the predominant eicosanoid generated by MPs. Mechanistically, 12(S)-HETE is produced through the concerted activity of secreted phospholipase A2 IIA (sPLA2-IIA), present in inflammatory fluids, and platelet-type 12-lipoxygenase (12-LO), expressed by platelet MPs. Platelet MPs convey an elaborate set of transcription factors and nucleic acids, and contain mitochondria. We observed that MPs and their cargo are internalized by activated neutrophils in the endomembrane system via 12(S)-HETE. Platelet MPs are found inside neutrophils isolated from the joints of arthritic patients, and are found in neutrophils only in the presence of sPLA2-IIA and 12-LO in an in vivo model of autoimmune inflammatory arthritis. Using a combination of genetically modified mice, we show that the coordinated action of sPLA2-IIA and 12-LO promotes inflammatory arthritis. These findings identify 12(S)-HETE as a trigger of platelet MP internalization by neutrophils, a mechanism highly relevant to inflammatory processes. Because sPLA2-IIA is induced during inflammation, and 12-LO expression is restricted mainly to platelets, these observations demonstrate that platelet MPs promote their internalization in recipient cells through highly regulated mechanisms.
Journal Article
Platelet microparticles are internalized in neutrophils via the concerted activity of 12-lipoxygenase and secreted phospholipase Aâ-IIA
by
Matthieu Rousseau
,
Jacques J. Tremblay
,
Michael H. Gelb
in
12-lipoxygenase
,
arthritis
,
cell communication
2015
Platelets are anucleated blood elements highly potent at generating extracellular vesicles (EVs) called microparticles (MPs). Whereas EVs are accepted as an important means of intercellular communication, the mechanisms underlying platelet MP internalization in recipient cells are poorly understood. Our lipidomic analyses identified 12(S)-hydroxyeicosatetranoic acid [12(S)-HETE] as the predominant eicosanoid generated by MPs. Mechanistically, 12(S)-HETE is produced through the concerted activity of secreted phospholipase A â IIA (sPLA â-IIA), present in inflammatory fluids, and platelet-type 12-lipoxygenase (12-LO), expressed by platelet MPs. Platelet MPs convey an elaborate set of transcription factors and nucleic acids, and contain mitochondria. We observed that MPs and their cargo are internalized by activated neutrophils in the endomembrane system via 12(S)-HETE. Platelet MPs are found inside neutrophils isolated from the joints of arthritic patients, and are found in neutrophils only in the presence of sPLA â-IIA and 12-LO in an in vivo model of autoimmune inflammatory arthritis. Using a combination of genetically modified mice, we show that the coordinated action of sPLA â-IIA and 12-LO promotes inflammatory arthritis. These findings identify 12(S)-HETE as a trigger of platelet MP internalization by neutrophils, a mechanism highly relevant to inflammatory processes. Because sPLA â-IIA is induced during inflammation, and 12-LO expression is restricted mainly to platelets, these observations demonstrate that platelet MPs promote their internalization in recipient cells through highly regulated mechanisms.
Journal Article
Validity of FuncUseRatio for ecological monitoring of functional arm use after stroke: toward precision neurorehabilitation
2026
The use of the paretic arm in activities of daily living after stroke is critical to prevent further decline in function over time. Accelerometers offer the opportunity to monitor arm activity during real-life daily activities in home environments. However, commonly used accelerometric metrics may be influenced by passive movements unrelated to functional arm use. In this study, we evaluate the validity of FuncUseRatio for monitoring activities of daily living after stroke.
Two experiments were conducted. Experiment 1 enrolled 23 healthy participants who performed 22 arm functional movements representative of activities of daily living. Movements of both arms were simultaneously recorded using wrist-worn accelerometers and a Vicon motion capture system allowing a direct comparison between accelerometer-derived forearm orientation and Vicon measurements (gold standard). Experiment 2 included 25 individuals after stroke who performed ecological activities (meal preparation, eating, and dressing). Arm movements were recorded using accelerometers and synchronized video analysis (ground truth), enabling comparison between accelerometer-derived FuncUseRatio and structured video-based arm-use computation.
In Experiment 1, forearm orientation estimated from accelerometer data showed excellent consistency with Vicon measurements under dynamic conditions required for FuncUse computation. The intraclass correlation coefficients (ICC) were ICC(C,1) = 0.92 (95% CI 0.82-0.96, p < 0.01) for the right forearm and ICC(C,1) = 0.94 (95% CI 0.86-0.97, p < 0.01) for the left forearm, confirming strong agreement between the two systems. In Experiment 2, FuncUseRatio derived from accelerometer data demonstrated excellent agreement with the structured video-based analysis ratio, considered the ground truth, with (ICC(A,1) = 0.96, 95% CI 0.90-0.98, p < 0.01).
The FuncUseRatio is a valid measure for assessing functional arm use during activities of daily living in ecologically relevant settings. Its implementation may enable early detection of reduced paretic arm use, including when the patient is at home, facilitate timely reassessment to understand its underlying causes, and thereby allow the implementation of specific arm rehabilitation strategies before any decline in function or participation occurs.
Journal Article
Crystallography of Growth Blocks in Spheroidal Graphite
by
Fundenberger, Jean Jacques
,
Brodu, Etienne
,
Bouzy, Emmanuel
in
Condensed Matter
,
Crystallography
,
Electron microscopes
2018
A better understanding of spheroidal graphite growth is expected in a near future thanks to widespread use of transmission electron microscopy. However, common transmission electron microscopy is quite time consuming and new indexing techniques are being developed, among them is transmission Kikuchi diffraction in a scanning electron microscope, a recent technique derived from electron backscatter diffraction. In the present work, on-axis transmission Kikuchi diffraction in scanning electron microscope, completed by transmission electron microscopy, was used with the objective of producing new observations on the microstructure of spheroidal graphite. This study shows that disorientations between blocks and sectors in spheroidal graphite are quite large in the early growth stage, which may be indicative of a competition process selecting the best orientations for achieving radial growth along the c direction of graphite.
Journal Article