Publications by authors named "Collard L"

Optical approaches to monitor neural activity are transforming neuroscience, owing to a fast-evolving palette of genetically encoded molecular reporters. However, the field still requires robust and label-free technologies to monitor the multifaceted biomolecular changes accompanying brain development, aging or disease. Here, we have developed vibrational fiber photometry as a low-invasive method for label-free monitoring of the biomolecular content of arbitrarily deep regions of the mouse brain in vivo through spontaneous Raman spectroscopy.

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Raman spectroscopy is a label-free, chemically specific optical technique that provides detailed information about the chemical composition and structure of the excited analyte. Because of this, there is growing research interest in miniaturizing Raman probes to reach deep regions of the body. Typically, such probes utilize multiple optical fibers to act as separate excitation/collection channels with optical filters attached to the distal facet to separate the collected signal from the background optical signal from the probe itself.

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The use of wavefront shaping has found extensive application to develop ultra-thin endoscopic techniques based on multimode optical fibers (MMF), leveraging on the ability to control modal interference at the fiber's distal end. Although several techniques have been developed to achieve MMF-based laser-scanning imaging, the use of short laser pulses is still a challenging application. This is due to the intrinsic delay and temporal broadening introduced by the fiber itself, which requires additional compensation optics on the reference beam during the calibration procedure.

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Achieving high-fidelity image transmission through turbid media is a significant challenge facing both the AI and photonic/optical communities. While this capability holds promise for a variety of applications, including data transfer, neural endoscopy, and multi-mode optical fiber-based imaging, conventional deep learning methods struggle to capture the nuances of light propagation, leading to weak generalization and limited reconstruction performance. To address this limitation, we investigated the non-locality present in the reconstructed images and discovered that conventional deep learning methods rely on specific features extracted from the training dataset rather than meticulously reconstructing each pixel.

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Objective: The COVID-19 pandemic required unprecedented changes to emergency medical services (EMS) educational frameworks in the United States. It is unclear if pandemic-related changes impacted paramedic educational outcomes. We aimed to evaluate curricular and performance changes resulting from the initial COVID-19 pandemic on paramedic educational programs.

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Introduction: Primary hyperoxaluria type 1 (PH1) is known for its variable clinical course, even within families. However, the extent of this heterogeneity has not been well-studied. We aimed to analyze intrafamilial clinical heterogeneity and disease course among siblings in a large cohort of familial PH1 cases.

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Creating plasmonic nanoparticles on a tapered optical fiber (TF) tip enables a remote surface-enhanced Raman scattering (SERS) sensing probe, ideal for challenging sampling scenarios like biological tissues, site-specific cells, on-site environmental monitoring, and deep brain structures. However, nanoparticle patterns fabricated from current bottom-up methods are mostly random, making geometry control difficult. Uneven statistical distribution, clustering, and multilayer deposition introduce uncertainty in correlating device performance with morphology.

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To promote improved trial design in upcoming randomized clinical trials in childhood chronic kidney disease (CKD), insight in the within- and inter-patient variability of uremic toxins with its nutritional, treatment- and patient-related confounding factors is of utmost importance. In this study, the within- and inter-patient variability of a selection of uremic toxins in a longitudinal cohort of children diagnosed with CKD was assessed, using the intraclass correlation coefficient (ICC) and the within-patient coefficient of variation (CV). Subsequently, the contribution of anthropometry, estimated glomerular filtration rate (eGFR), dietary fiber and protein, and use of (prophylactic) antibiotics to uremic toxin variability was evaluated.

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Within the realm of optical neural interfaces, the exploration of plasmonic resonances to interact with neural cells has captured increasing attention among the neuroscience community. The interplay of light with conduction electrons in nanometer-sized metallic nanostructures can induce plasmonic resonances, showcasing a versatile capability to both sense and trigger cellular events. We describe the perspective of generating propagating or localized surface plasmon polaritons on the tip of an optical neural implant, widening the possibility for neuroscience labs to explore the potential of plasmonic neural interfaces.

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Introduction: Growth failure is considered the most important clinical outcome parameter in childhood chronic kidney disease (CKD). Central to the pathophysiology of growth failure is the presence of a chronic proinflammatory state, presumed to be partly driven by the accumulation of uremic toxins. In this study, we assessed the association between uremic toxin concentrations and height velocity in a longitudinal multicentric prospective pediatric CKD cohort of (pre)school-aged children and children during pubertal stages.

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Artificial intelligence has emerged as promising tool to decode an image transmitted through a multimode fiber (MMF) by applying deep learning techniques. By transmitting thousands of images through the MMF, deep neural networks (DNNs) are able to decipher the seemingly random output speckle patterns and unveil the intrinsic input-output relationship. High fidelity reconstruction is obtained for datasets with a large degree of homogeneity, which underutilizes the capacity of the combined MMF-DNN system.

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We here highlight the importance of stoichiometry for simultaneous cocrystal resolution. Focusing on combining the racemates of binol and proline, we show that a 1 : 2 ratio leads to formation of a full racemic compound, whereas a 2 : 1 ratio, leads to conglomerate formation, with simultaneous resolution of both binol and proline. Playing on stoichiometry, one achieves a reversible switch between the racemic compound and conglomerate.

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A one-carbon homologation of Knoevenagel adducts enabling the insertion of a CHAr fragment is reported. The strategy involves a sulfur ylide mediated cyclopropanation followed by the rearrangement of cyclopropanes and enables the synthesis of a series of benzhydryl derivatives. Mechanistic studies reveal that the cyclopropane rearrangement involves a Lewis acid catalyzed ring-opening followed by the 1,2-migration of an aryl group.

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Article Synopsis
  • Pre-shaping light for multimode fibers allows for innovative imaging techniques by controlling amplitude distributions at the fiber's tip, which involves analyzing a scrambled light pattern created by the fiber.
  • Recent methods utilizing an internal reference beam have shown improved stability in interferometric setups, but criticisms arise regarding their influence on measurement accuracy and potential "blind spots."
  • This study demonstrates that optimizing the choice of internal reference beam can enhance the focusing efficiency of the calibration process by several percent.
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Background: Initial paramedic education must have sufficient rigor and appropriate resources to prepare graduates to provide lifesaving prehospital care. Despite required national paramedic accreditation, there is substantial variability in paramedic pass rates that may be related to program infrastructure and clinical support. Our objective was to evaluate US paramedic program resources and identify common deficiencies that may affect program completion.

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Objective: Recent concerns for the strength and stability of the emergency medical services (EMS) workforce have fueled interest in enhancing the entry of EMS clinicians into the workforce. However, the educational challenges associated with workforce entry remain unclear. Our objective was to evaluate the educational pathway of entry into the EMS workforce and to identify factors that lead to the loss of potential EMS clinicians.

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Background: This cross-sectional study investigated quality of life (QoL) and illness-related parental stress in children with kidney diseases by (1) comparing mean levels of these two variables between several kidney disease categories; (2) exploring correlations between QoL and parental stress; and (3) describing which disease category reports lowest QoL and highest parental stress.

Methods: We included 295 patients with a kidney disease (0-18 years) and their parents, followed at 6 reference centers for pediatric nephrology. Children's QoL was assessed by the PedsQL™ 4.

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Article Synopsis
  • Integration of plasmonic nanostructures with fiber-optic neural probes allows for label-free molecular detection using surface-enhanced Raman spectroscopy (SERS), opening new prospects for brain function analysis.
  • A novel tapered optical fiber (TF) coated with gold nanoislands (NIs) has been developed to detect neurotransmitters at micromolar concentrations with minimal invasiveness.
  • The innovative fabrication technique achieves a detection limit of 10 m for substances like rhodamine 6G, serotonin, and dopamine, indicating potential for future in vivo applications in neurotechnology.
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Introduction: Swimming is composed of several phases. One of them is done underwater in apnea. Although this phase takes an important part of the performance, it is not taught much because of the risk it entails.

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We present a thought-provoking development in chiral resolution. Using a resolving agent of a given handedness, L-proline, we show that both R- and S-enantiomers of mandelic acid can be resolved from a racemic mixture simply by varying the stoichiometry. We are the first to report this specific feature, achieved by the existence of stoichiometrically diverse cocrystal systems between R- and S-mandelic acid and L-proline.

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Article Synopsis
  • Infantile oxalosis, a severe form of primary hyperoxaluria type 1, leads to end-stage kidney disease (ESKD) in infants, with a study analyzing 95 cases from 1980 to 2018 revealing critical patient outcomes.
  • Among the findings, the median age for ESKD onset was just 0.4 years, with a significant number of patients (30%) dying by the age of 1.4 years despite advancements in survival rates for those born post-2000.
  • Systemic oxalosis was prevalent in almost all patients screened, highlighting the need for ongoing research into the genetic variability observed within families affected by infantile oxalosis.
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Background: Primary hyperoxalurias (PHs) are rare genetic diseases that increase the endogenous level of oxalate, a waste metabolite excreted predominantly by the kidneys and also the gut. Treatments aim to improve oxalate excretion, or reduce oxalate generation, to prevent kidney function deterioration. Oxalobacter formigenes is an oxalate metabolizing bacterium.

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Integration of plasmonic structures on step-index optical fibers is attracting interest for both applications and fundamental studies. However, the possibility to dynamically control the coupling between the guided light fields and the plasmonic resonances is hindered by the turbidity of light propagation in multimode fibers (MMFs). This pivotal point strongly limits the range of studies that can benefit from nanostructured fiber optics.

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Context: Pain is a primary reason individuals attend an Emergency Department (ED), and its management is a concern.

Objectives: Change in symptoms and physiologic variables at 3 time points pre-post a ten-minute St. John Ambulance therapy dog team visit compared to no visit in ED patients who experienced pain.

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