Publications by authors named "Radder J"

Article Synopsis
  • Critical illness alters the human microbiome, affecting the oral, lung, and gut bacteria in mechanically ventilated patients, leading to reduced microbial diversity and increased pathogens.
  • Advanced DNA sequencing methods were used to analyze the microbiota of 479 patients, revealing that clinical factors like COPD, immunosuppression, and antibiotic use influence the patterns of dysbiosis.
  • Lung microbiota diversity and composition were found to predict patient survival better than traditional clinical predictors, suggesting the potential for using microbiome analysis as a tool for improving patient outcomes in critical care settings.
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Purpose: We examined magnetic field dependent SNR gains and ability to capture them with multichannel receive arrays for human head imaging in going from 7 T, the most commonly used ultrahigh magnetic field (UHF) platform at the present, to 10.5 T, which represents the emerging new frontier of >10 T in UHFs.

Methods: Electromagnetic (EM) models of 31-channel and 63-channel multichannel arrays built for 10.

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Acute inflammation is heterogeneous in critical illness and predictive of outcome. We hypothesized that genetic variability in novel, yet common, gene variants contributes to this heterogeneity and could stratify patient outcomes. We searched algorithmically for significant differences in systemic inflammatory mediators associated with any of 551,839 SNPs in one derivation (n = 380 patients with blunt trauma) and two validation (n = 75 trauma and n = 537 non-trauma patients) cohorts.

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Respiratory microbial dysbiosis is associated with acute respiratory distress syndrome (ARDS) and hospital-acquired pneumonia (HAP) in critically ill patients. However, we lack reproducible respiratory microbiome signatures that can increase our understanding of these conditions and potential treatments. Here, we analyze 16S rRNA sequencing data from 2,177 respiratory samples collected from 1,029 critically ill patients (21.

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Article Synopsis
  • Critical illness alters the microbiome in the oral, lung, and gut areas, leading to significant changes like decreased diversity and increased harmful bacteria.
  • A study of 479 patients on mechanical ventilation revealed that factors like chronic obstructive pulmonary disease and antibiotic use influence these changes.
  • Lung microbiota diversity was found to independently predict patient survival, suggesting it could be useful for guiding treatment in critically ill individuals and indicating the potential for targeted microbiome therapies.
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Critical illness can disrupt the composition and function of the microbiome, yet comprehensive longitudinal studies are lacking. We conducted a longitudinal analysis of oral, lung, and gut microbiota in a large cohort of 479 mechanically ventilated patients with acute respiratory failure. Progressive dysbiosis emerged in all three body compartments, characterized by reduced alpha diversity, depletion of obligate anaerobe bacteria, and pathogen enrichment.

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In this letter, we evaluate antenna designs for ultra-high frequency and field (UHF) human brain magnetic resonance imaging (MRI) at 10.5 tesla (T). Although MRI at such UHF is expected to provide major signal-to-noise gains, the frequency of interest, 447 MHz, presents us with challenges regarding improved B efficiency, image homogeneity, specific absorption rate (SAR), and antenna element decoupling for array configurations.

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Purpose: To expand on the previously developed -encoding technique, frequency-modulated Rabi-encoded echoes (FREE), to perform accelerated image acquisition by collecting multiple lines of k-space in an echo train.

Methods: FREE uses adiabatic full-passage pulses and a spatially varying RF field to encode unique spatial information without the use of traditional B gradients. The original implementation relied on acquiring single lines of k-space, leading to long acquisitions.

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Purpose: To correct image distortions that result from nonlinear spatial variation in the transmit RF field amplitude ( ) when performing spatial encoding with the method called frequency-modulated Rabi encoded echoes (FREE).

Theory And Methods: An algorithm developed to correct image distortion resulting from the use of nonlinear static field (B ) gradients in standard MRI is adapted herein to correct image distortion arising from a nonlinear -gradient field in FREE. From a -map, the algorithm performs linear interpolation and intensity scaling to correct the image.

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For ultra-high field and frequency (UHF) magnetic resonance imaging (MRI), the associated short wavelengths in biological tissues leads to penetration and homogeneity issues at 10.5 tesla (T) and require antenna transmit arrays for efficiently generated 447 MHz B fields (defined as the transmit radiofrequency (RF) magnetic field generated by RF coils). Previously, we evaluated a 16-channel combined loop + dipole antenna (LD) 10.

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Purpose: Investigating the designs and effects of high dielectric constant (HDC) materials in the shape of a conformal helmet on the enhancement of RF field and reduction of specific absorption rate at 10.5 T for human brain studies.

Methods: A continuous and a segmented four-piece HDC helmet fit to a human head inside an eight-channel fractionated-dipole array were constructed and studied with a phantom and a human head model using computer electromagnetic simulations.

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Purpose: Receive array layout, noise mitigation, and B field strength are crucial contributors to SNR and parallel-imaging performance. Here, we investigate SNR and parallel-imaging gains at 10.5 T compared with 7 T using 32-channel receive arrays at both fields.

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Airway hydration and ciliary function are critical to airway homeostasis and dysregulated in chronic obstructive pulmonary disease (COPD), which is impacted by cigarette smoking and has no therapeutic options. We utilized a high-copy cDNA library genetic selection approach in the amoeba to identify genetic protectors to cigarette smoke. Members of the mitochondrial ADP/ATP transporter family adenine nucleotide translocase (ANT) are protective against cigarette smoke in and human bronchial epithelial cells.

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A 32-channel RF coil was developed for brain imaging of anesthetized non-human primates (rhesus macaque) at 10.5 T. The coil is composed of an 8-channel dipole transmit/receive array, close-fitting 16-channel loop receive array headcap, and 8-channel loop receive array lower insert.

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Purpose: In this work, we investigated how the position of the radiofrequency (RF) shield can affect the signal-to-noise ratio (SNR) of a receive RF coil. Our aim was to obtain physical insight for the design of a 10.5T 32-channel head coil, subject to the constraints on the diameter of the RF shield imposed by the head gradient coil geometry.

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We evaluated a 16-channel loop + dipole (LD) transceiver antenna array with improved specific absorption rate (SAR) efficiency for 10.5 Tesla (T) human head imaging apsplications. Three different array designs with equal inner dimensions were considered: an 8-channel dipole antenna, an 8-channel loop, and a 16-channel LD antenna arrays.

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The type of IgG subclasses induced by vaccination is an important determinant of vaccine efficacy because the IgG subclasses vary in their biological function. The goal of this study was to determine the influence of the genetic background on the production and duration of vaccine-induced IgG subclasses. IgG1, IgG2b, and IgG3 titers against diphtheria toxoid (DT), pertussis toxin (PT), filamentous hemagglutinin (FHA), and pertactin (Prn) were measured in mice from 28 different inbred and wild-derived strains vaccinated with an aluminum hydroxide-adjuvanted DTaP vaccine.

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Gene expression of BAL cells, which samples the cellular milieu within the lower respiratory tract, has not been well studied in severe asthma. To identify new biomolecular mechanisms underlying severe asthma by an unbiased, detailed interrogation of global gene expression. BAL cell expression was profiled in 154 asthma and control subjects.

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Purpose: Despite the clear synergy between high channel counts in a receive array and magnetic fields ≥ 7 Tesla, to date such systems have been restricted to a maximum of 32 channels. Here, we examine SNR gains at 7 Tesla in unaccelerated and accelerated images with a 64-receive channel (64Rx) RF coil.

Methods: A 64Rx coil was built using circular loops tiled in 2 separable sections of a close-fitting form; custom designed preamplifier boards were integrated into each coil element.

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The acute respiratory distress syndrome (ARDS) causes an estimated 70,000 US deaths annually. Multiple pharmacologic interventions for ARDS have been tested and failed. An unmet need is a suitable laboratory human model to predictively assess emerging therapeutics on organ function in ARDS.

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Chronic obstructive pulmonary disease (COPD) is caused by a complex interaction of environmental exposures, most commonly cigarette smoke, and genetic factors. Chronic cigarette smoke exposure in the mouse is a commonly used animal model of COPD. We aimed to expand our knowledge about the variable susceptibility of inbred strains to this model and test for genetic variants associated with this trait.

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