Publications by authors named "RJ McDonald"

Article Synopsis
  • The study investigates the role of the hippocampus (HPC) and amygdala in memory formation, particularly focusing on retrograde amnesia that occurs after HPC disruption.
  • Findings reveal that damage to the HPC does not affect conditioned place preference (CPP) tasks, which rely on the basolateral amygdala, suggesting that not all learning tasks require HPC involvement.
  • Additional experiments using the Morris water task indicate that while HPC damage impairs performance, other memory networks can't fully compensate when certain training methods are used, highlighting the complexity of memory processing.
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Evidence from neurophysiological and genetic studies demonstrates that activity sparsity-the proportion of neurons that are active at a given time in a population-systematically varies across the canonical trisynaptic circuit of the hippocampus. Recent work has also shown that sparsity varies across the hippocampal dorsoventral (long) axis, wherein activity is sparser in ventral than dorsal regions. While the hippocampus has a critical role in long-term memory (LTM), whether sparsity across the trisynaptic circuit and hippocampal long axis is task-dependent or invariant remains unknown.

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Background: The goal of these experiments was to determine which learning and memory system(s) were necessary for the retention of visual discriminations and subsequent acquisition of a second problem. The dorsal striatum should be involved in the acquisition and expression of this task based on previous work implicating this region in instrumental learning and memory processes. The perirhinal cortex has been implicated in learning and memory processes associated with visual information like objects, and pictures and may also play a role in the acquisition and/or retention of visual discriminations.

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Contrast media are an indispensable adjunct to pediatric imaging. The most common include iodine-based contrast media for CT and fluoroscopy, gadolinium-based contrast media and iron-oxide nanoparticles for MRI, and microbubbles for ultrasound. Although many of the considerations in the routine use of contrast media in infants and children (relating for example to renal function, allergic-like reactions, GBCM deposition, and extravasations) are similar to considerations in adult patients, some important differences exist.

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Article Synopsis
  • - Deep Reinforcement Learning (DRL) is used to simulate how biological agents learn based on rewards, and researchers modified DRL to mimic the effects of dendritic spine loss seen in major depressive disorder (MDD).
  • - This simulated spine loss led to various MDD-like behaviors in the AI, such as loss of pleasure (anhedonia), increased impatience for rewards (temporal discounting), and changes in how the AI explores or exploits options.
  • - The findings suggest that MDD may be more related to reduced brain connectivity rather than just chemical imbalances, indicating potential treatment avenues that focus on enhancing brain plasticity and synapse formation.
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Article Synopsis
  • Iodinated contrast material (ICM) is essential for various radiologic exams, but its use has been limited due to fears of kidney damage and other health risks.
  • Recent studies indicate that cases of acute kidney injury (AKI) previously attributed to ICM are often due to other factors or normal kidney function variability.
  • This study aims to outline the latest insights on contrast-induced AKI, covering its frequency, consequences, risk factors, and ways to prevent it.
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Article Synopsis
  • Idiopathic granulomatous mastitis is a rare and chronic breast inflammation that can resemble breast cancer, with its cause often unknown.
  • The case discusses a 66-year-old woman who had an initial benign biopsy of her left breast, which later developed a hematoma but appeared stable for a year.
  • After 21 months, the hematoma unexpectedly grew, leading to an ultrasound-guided biopsy that diagnosed her with granulomatous mastitis.
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IV contrast media improve the diagnostic power of radiology examinations. These media include gadolinium-based contrast media and iron-oxide nanoparticles for MRI, iodinated contrast material for CT, microbubbles for ultrasound, and radiopharmaceuticals for nuclear medicine. As for all medications, contrast media carry risks, which may be heightened in the conditions of pregnancy and lactation.

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Trichorhinophalangeal syndrome type 1 (TRPS1) has been reported to be a sensitive and specific immunohistochemical (IHC) marker for breast carcinomas, especially when determining primary site of origin. However, there is limited data on TRPS1 expression in prostate and bladder cancers. A two-phase study was performed with 1) an exploratory cohort analyzing TRPS1 gene alterations in prostate, bladder, and breast carcinoma and TPRS1 mRNA expression data in prostate and bladder carcinoma; and 2) TRPS1 and GATA3 IHC in a confirmatory cohort in prostate, bladder, and breast carcinoma samples.

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Objective: To assess the effects of patient variables, examination variables, and seasonality on allergic-like and physiologic reactions to iodinated contrast material (ICM).

Patients And Methods: All ICM-enhanced computed tomography (CT) examinations performed from June 1, 2009, to May 9, 2017, at our institution were included. Reactions were identified and categorized as allergic-like or physiologic and mild, moderate, or severe.

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Education, occupation, and an active lifestyle, comprising enhanced social, physical, and mental components are associated with improved cognitive functions in aged people and may delay the progression of various neurodegenerative diseases including Alzheimer's disease. To investigate this protective effect, 3-month-old APP mice were exposed to repeated single- or multi-domain cognitive training. Cognitive training was given at the age of 3, 6, & 9 months.

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Extravasation of iodinated contrast material (ICM) is an uncommon complication (0.1%-1.2%) following intravenous injection for computed tomography exams and other procedures.

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Iodinated contrast material (ICM) has revolutionized the field of diagnostic radiology through improvements in diagnostic performance and the expansion of clinical indications for radiographic and CT examinations. Historically, nephrotoxicity was a feared complication of ICM use, thought to be associated with a significant risk of morbidity and mortality. Such fears often precluded the use of ICM in imaging evaluations, commonly at the expense of diagnostic performance and timely diagnosis.

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Purpose: Dental amalgam contains mercury and is commonly used in dental restorations. The impact of MRI on mercury excretion from dental amalgam is not well understood across clinical field strengths, especially 7T. We investigated the effects of MRI exposure on mercury excretion using fresh, lab-created dental amalgam restorations and in extracted teeth with old, pre-existing restorations.

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Objective: CD47 is an antiphagocytic molecule that plays a critical role in immune surveillance. A variety of malignancies have been shown to evade the immune system by increasing the expression of CD47 on the cell surface. As a result, anti-CD47 therapy is under clinical investigation for a subset of these tumors.

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The amygdala has been implicated in a variety of functions linked to emotions. One popular view is that the amygdala modulates consolidation in other brain systems thought to be mainly involved in learning and memory processes. This series of experiments represents a further exploration into the role of the amygdala in memory modulation and consolidation.

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Matrix assisted laser desorption/ionization imaging has greatly improved our understanding of spatial biology, however a robust bioinformatic pipeline for data analysis is lacking. Here, we demonstrate the application of high-dimensionality reduction/spatial clustering and histopathological annotation of matrix assisted laser desorption/ionization imaging datasets to assess tissue metabolic heterogeneity in human lung diseases. Using metabolic features identified from this pipeline, we hypothesize that metabolic channeling between glycogen and N-linked glycans is a critical metabolic process favoring pulmonary fibrosis progression.

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Prenatal experiences can influence offspring physiology and behaviour through the lifespan. Various forms of prenatal stress impair adult learning and memory function and can lead to increased occurrence of anxiety and depression. Clinical work suggests that prenatal stress and maternal depression lead to similar outcomes in children and adolescents, however the long-term effects of maternal depression are less established, particularly in well controlled animal models.

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Objective: To examine follow-up care in patients with a history of acute allergic-like reaction to iodinated contrast material (ICM), including subsequent imaging management, allergy consultation, and repeat ICM exposure and reactions.

Methods: All patients who had a moderate or severe acute allergic-like reaction to ICM after contrast-enhanced CT (CECT) examination from June 1, 2009, to January 1, 2022, at our institution were included. Chart review was performed to determine (1) whether subsequent imaging was not performed or was altered in these patients, (2) whether the patient underwent a subsequent CECT examination, and (3) whether the patient had an allergist consultation.

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Chronic inflammatory diseases are highly comorbid with anxiety in humans. The extent to which chronic inflammation is responsible for this relationship remains to be determined. We therefore tested the hypothesis that prolonged, but not brief, gut inflammation is sufficient to evoke anxiety-related behaviours in mice.

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Background: An active lifestyle is associated with improved cognitive functions in aged people and may prevent or slow down the progression of various neurodegenerative diseases including Alzheimer's disease (AD). To investigate these protective effects, male APP mice were exposed to long-term voluntary exercise.

Methods: Three-month-old AD mice were housed in a cage supplemented with a running wheel for 9 months for long-term exercise.

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Covid-19 has been front and center in the global landscape since the beginning of 2020. In response, the scientific field has dedicated enormous amounts of resources to researching the virus and its effects. The number of times Covid-19 publications are being cited throughout the literature appears remarkably high but has not been directly compared to non-Covid-19 papers in the same journals over an extended period.

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