47 results on '"Mason LJ"'
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2. Massive amplitudes from twistors on the worldsheet
- Author
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Albonico, G and Mason, LJ
- Abstract
The subject of this thesis are ambitwistor string models that describe massive particles by gauging currents to implement a symmetry reduction. Because the amplitude formulae one obtains as correlators in these models are really reductions of the ones presented in [1, 2], the body of the thesis will open with a discussion of properties and features of the six-dimensional superamplitudes that the massive formulae will inherit. Two different instances of symmetry reduction in the ambitwistor string will be considered. The first is a massive version of the RNS ambitwistor string. This provides a derivation of massive amplitude formulae that have support on massive scattering equations such as the ones predicted by Dolan and Goddard [3] and Naculich [4], together with a solid understanding of mass assignment both to external and propagating particles. The second consists of four dimensional twistorial models that will be shown to have an alternative interpretation as theories of maps into the phase space of complexified massive particles. This representation is more suitable to describe supersymmetric theories, such as the Coulomb branch of N = 4 sYM. An interesting class of theories is presented, which is obtained by symmetry reduction along the R-symmetry generators. For supergravity, this produces CSS gauged supergravities in four dimensions. In these theories a novel instance of ‘massive’ double copy structure arises.
- Published
- 2023
3. Validating the Use of Continuous Glucose Monitors With Nondiabetic Recreational Runners.
- Author
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Mason LJ, Hartwig T, and Greene D
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- Humans, Adult, Male, Oxygen Consumption, Female, Reproducibility of Results, Postprandial Period, Arm, Exercise Test, Middle Aged, Running physiology, Blood Glucose analysis, Blood Glucose Self-Monitoring instrumentation, Blood Glucose Self-Monitoring methods
- Abstract
Purpose: Continuous glucose monitors (CGMs) are becoming increasingly popular among endurance athletes despite unconfirmed accuracy. We assessed the concurrent validity of the FreeStyle Libre 2 worn on 2 different sites at rest, during steady-state running, and postprandial., Methods: Thirteen nondiabetic, well-trained recreational runners (age = 40 [8] y, maximal aerobic oxygen consumption = 46.1 [6.4] mL·kg-1·min-1) wore a CGM on the upper arm and chest while treadmill running for 30, 60, and 90 minutes at intensities corresponding to 50%, 60%, and 70% of maximal aerobic oxygen consumption, respectively. Glucose was measured by manually scanning CGMs and obtaining a finger-prick capillary blood glucose sample. Mean absolute relative difference, time in range, and continuous glucose Clarke error grid analysis were used to compare paired CGM and blood glucose readings., Results: Across all intensities of steady-state running, we found a mean absolute relative difference of 13.8 (10.9) for the arm and 11.4 (9.0) for the chest. The coefficient of variation exceeded 70%. Approximately 47% of arm and 50% of chest paired glucose measurements had an absolute difference ≤10%. Continuous glucose Clarke error grid analysis indicated 99.8% (arm) and 99.6% (chest) CGM data fell in clinically acceptable zones A and B. Time-in-range analysis showed reduced accuracy at lower glucose levels. However, CGMs accurately detected trends in mean glucose readings over time., Conclusions: CGMs are not valid for point glucose monitoring but appear to be valid for monitoring glucose trends during steady-state exercise. Accuracy is similar for arm and chest. Further research is needed to determine whether CGMs can detect important events such as hypoglycemia during exercise.
- Published
- 2024
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4. Pediatric anesthesia in North America.
- Author
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Srinivasan I, Whyte S, Bailey K, Antrobus T, Hinkson-LaCorbinière K, Martin TW, Cravero JP, and Mason LJ
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- Humans, Child, North America, Anesthesia, United States, Canada, Pediatric Anesthesia, Pediatrics methods, Anesthesiology education
- Abstract
Background and Objectives: This educational review outlines the current landscape of pediatric anesthesia training, care delivery, and challenges across Canada, Barbados, and the United States., Descriptions and Conclusions: Approximately 5% of Canadian children undergo general anesthesia annually, administered by fellowship-trained pediatric anesthesiologists in children's hospitals, general anesthesiologists in community hospitals, or family practice anesthesiologists in underserved regions. In Canada, the focus is on national-level evaluation and accreditation of pediatric anesthesia fellowship training, addressing challenges arising from workforce shortages, particularly in remote areas. Barbados, a Caribbean nation, lacks dedicated pediatric hospitals but has provided pediatric anesthesia since 1972 through anesthetists with additional training. Challenges in its development, common to low-middle-income countries, include inadequate infrastructure and workforce shortages. Increased awareness of pediatric anesthesia as a sub-specialty could enhance perioperative care for Barbadian children. Pediatric anesthesia encompasses various specialties in the United States, with pediatric anesthesiologists playing a foundational role. Challenges faced include recruitment and retention difficulties, supply-chain shortages, and the proliferation of anesthesia sites, all impacting the delivery of modern, high-quality, and cost-effective patient care. Collaborative efforts at national and organizational levels strive to improve the quality and safety of pediatric anesthesia care in the United States., (© 2024 John Wiley & Sons Ltd.)
- Published
- 2024
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5. Effect of Hypoxia on the Lethal Mortality Time of Adult Sitophilus oryzae L.
- Author
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Kandel P, Scharf ME, Mason LJ, and Baributsa D
- Abstract
Sitophilus oryzae is one of the most destructive pests of stored grains. It leads to significant quantitative and qualitative losses, resulting in food and income insecurity among farmers. Chemical pesticides are the most common methods used by farmers and other grain value chain actors to manage this pest. However, pesticides are increasingly becoming unattractive for pest control due to health hazards posed to applicators, consumers, the environment, and insect resistance. Modified atmospheres have the potential to manage stored insect pests as an alternative to pesticides. There is limited understanding of when insect pests die when grain is stored in airtight containers. This experiment was conducted to assess the time required to reach mortality of adult S. oryzae when exposed to 1, 3, and 5% oxygen levels. Results revealed that the LT50 for 1, 3, and 5% of oxygen were reached after 69.7 h, 187.8 h, and 386.6 h of exposure, respectively. No adult emergence was observed on infested grains following exposure to 1 and 3% oxygen levels. This result provides vital rationale for storing grain in hermetic storage conditions for at least 39 days to achieve adult S. oryzae mortality and minimize grain reinfestation.
- Published
- 2021
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6. Professorial Advancement Initiative: A Cross-Institutional Collaboration to Increase Faculty Diversity in STEM.
- Author
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Yadav A, Smith MJT, Farber CR, and Mason LJ
- Abstract
In this paper, we describe the model for faculty diversity developed as part of the Professorial Advancement Initiative (PAI) funded under the NSF AGEP program. The PAI, consisting of 12 of the 14 Big Ten Academic Alliance universities, had the goal of doubling the rate at which the universities hired tenure-track minoritized faculty, defined by National Science Foundation as African Americans, Hispanic/Latinx, Native Americans, and Pacific Islanders. This paper reviews the key programmatic elements of the PAI and discusses lessons learned and the practices developed that helped the Alliance achieve its faculty diversity goal., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Yadav, Smith, Farber and Mason.)
- Published
- 2021
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7. Determining baseline toxicity of ozone against an insecticide-susceptible strain of the common bed bug, Cimex lectularius L. under laboratory conditions.
- Author
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Feston J, Gaire S, Fardisi M, Mason LJ, and Gondhalekar AD
- Subjects
- Animals, Humans, Laboratories, Nymph, Bedbugs, Insecticides pharmacology, Ozone pharmacology
- Abstract
Background: Ozone gas is commercially used for deodorization and microbial control. Its efficacy against stored product insect pests is well documented. In the midst of the common bed bug (Cimex lectularius L.) outbreak, claims were made that ozone gas was effective for their control. This study was conducted to determine baseline ozone concentrations and exposure times required for the control of an insecticide-susceptible C. lectularius strain under laboratory conditions. Dichlorvos (DDVP), an organophosphate class fumigant insecticide was used as a positive control., Results: Nymphs and adults were more susceptible to ozone than eggs. Complete (100%) nymph and adult mortality was achieved at an ozone concentration (C) of 1500 ppm and exposure time (T) of 180 min, or concentration × time product (CT) of 270 000 ppm-min, whereas eggs required an eightfold higher CT (2 040 000 ppm-min). DDVP vapor was 2070-, 2542- and 450-fold more potent than ozone, against nymphs, adults and eggs, respectively., Conclusions: Baseline ozone toxicity data provide insights on the practicality of using this gas for the management of common bed bugs. High ozone CT products required for C. lectularius control, particularly eggs, suggest that its use for treating infested human dwellings is not feasible due to logistic, safety and monetary concerns. © 2020 Society of Chemical Industry., (© 2020 Society of Chemical Industry.)
- Published
- 2020
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8. High-Tech and Tactile: Cognitive Enrichment for Zoo-Housed Gorillas.
- Author
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Clark FE, Gray SI, Bennett P, Mason LJ, and Burgess KV
- Abstract
The field of environmental enrichment for zoo animals, particularly great apes, has been revived by technological advancements such as touchscreen interfaces and motion sensors. However, direct animal-computer interaction (ACI) is impractical or undesirable for many zoos. We developed a modular cuboid puzzle maze for the troop of six Western lowland gorillas ( Gorilla gorilla gorilla ) at Bristol Zoo Gardens, United Kingdom. The gorillas could use their fingers or tools to interact with interconnected modules and remove food rewards. Twelve modules could be interchanged within the frame to create novel iterations with every trial. We took a screen-free approach to enrichment: substituting ACI for tactile, physically complex device components, in addition to hidden automatic sensors, and cameras to log device use. The current study evaluated the gorillas' behavioral responses to the device, and evaluated it as a form of "cognitive enrichment." Five out of six gorillas used the device, during monthly trials of 1 h duration, over a 6 month period. All users were female including two infants, and there were significant individual differences in duration of device use. The successful extraction of food rewards was only performed by the three tool-using gorillas. Device use did not diminish over time, and gorillas took turns to use the device alone or as one mother-infant dyad. Our results suggest that the device was a form of cognitive enrichment for the study troop because it allowed gorillas to solve novel challenges, and device use was not associated with behavioral indicators of stress or frustration. However, device exposure had no significant effects on gorilla activity budgets. The device has the potential to be a sustainable enrichment method in the long-term, tailored to individual gorilla skill levels and motivations. Our study represents a technological advancement for gorilla enrichment, an area which had been particularly overlooked until now. We wholly encourage the continued development of this physical maze system for other great apes under human care, with or without computer logging technology.
- Published
- 2019
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9. Efficacy of Hypoxia Against Tribolium castaneum (Coleoptera: Tenebrionidae) Throughout Ontogeny.
- Author
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Kharel K, Mason LJ, Murdock LL, and Baributsa D
- Subjects
- Animals, Hypoxia, Larva, Pupa, Coleoptera, Tribolium
- Abstract
Hermetic grain storage technology offers a viable chemical-free approach to control storage insects. However, there is limited knowledge on how hypoxia affects the survival of insect life stages during grain storage in hermetic bags. We exposed Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) eggs (2 d), young larvae (7 d), old larvae (21 d), pupae (28 d), and adults (2 d after emergence) to 2, 4, 8, and 20.9% oxygen levels for 1, 3, 5, 10, and 15 d and assessed subsequent mortality. At 2% oxygen, complete mortality was achieved in 3 d for eggs and young larvae, 10 d for old larvae and pupae, and 15 d for adults. At 4% oxygen, 15 d were required to kill all eggs and old larvae but not the other insect life stages. At 8% oxygen after 15 d, complete mortality of any insect life stage was not observed; but even a relatively short exposure (1-3 d) caused significant developmental delays in immature insects. Our study shows potential utility of hermetic technology for control of T. castaneum, but internal oxygen should be maintained below 2% level for at least 15 d for complete control. Increased oxygen levels improved the development of all insect life stages leading to increased adult emergence. There is a need to explore exposure time required to achieve complete mortality of all insect life stage above the 2% oxygen level., (© The Author(s) 2019. Published by Oxford University Press on behalf of Entomological Society of America.)
- Published
- 2019
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10. A time-saving method for sealing Purdue Improved Crop Storage (PICS) bags.
- Author
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Kharel K, Mason LJ, Williams SB, Murdock LL, Baoua IB, and Baributsa D
- Abstract
Purdue Improved Crop Storage (PICS) bags were designed to reduce grain storage losses on smallholder farms. The bag consists of three layers: two high-density polyethylene liners fitted inside a woven polypropylene bag. Recently, farmer groups, development relief programs, and government food security agencies have shown interest in PICS bags for large-scale use. PICS bags are conventionally closed by a twist-tie (TT) method, which involves twisting, folding, and tying the lip of each layer individually with a cord. This is not only time and labor intensive, but also may affect the integrity of the liners. We evaluated three new bag closure methods: i) inner liner rolled onto itself and middle liner fold-tied (IR), ii) both liners folded together and tied (FT), and iii) both liners folded and tied separately (FS), along with the conventional twist tie (TT) method. The time to close partially or fully filled 50 kg-capacity PICS bags filled with maize grain was assessed. Results showed that FT was the most time-saving method, reducing bag sealing time by >34% versus the usual TT method. The average internal oxygen levels reached <2% within a week in bags containing grain highly infested with Sitophilus zeamais , while it remained >5% levels for less-infested bags. In both cases, insect population growth was suppressed. Oxygen depletion rates among tying methods remained the same regardless of the closure method used. When large numbers of bags need to be closed, the time-saving FT method is a good alternative PICS sealing method over the conventional twist-tie approach.
- Published
- 2018
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11. Twistor theory at fifty: from contour integrals to twistor strings.
- Author
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Atiyah M, Dunajski M, and Mason LJ
- Abstract
We review aspects of twistor theory, its aims and achievements spanning the last five decades. In the twistor approach, space-time is secondary with events being derived objects that correspond to compact holomorphic curves in a complex threefold-the twistor space. After giving an elementary construction of this space, we demonstrate how solutions to linear and nonlinear equations of mathematical physics-anti-self-duality equations on Yang-Mills or conformal curvature-can be encoded into twistor cohomology. These twistor correspondences yield explicit examples of Yang-Mills and gravitational instantons, which we review. They also underlie the twistor approach to integrability: the solitonic systems arise as symmetry reductions of anti-self-dual (ASD) Yang-Mills equations, and Einstein-Weyl dispersionless systems are reductions of ASD conformal equations. We then review the holomorphic string theories in twistor and ambitwistor spaces, and explain how these theories give rise to remarkable new formulae for the computation of quantum scattering amplitudes. Finally, we discuss the Newtonian limit of twistor theory and its possible role in Penrose's proposal for a role of gravity in quantum collapse of a wave function., Competing Interests: We declare we have no competing interests.
- Published
- 2017
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12. Essential role for CCR6 in certain inflammatory diseases demonstrated using specific antagonist and knockin mice.
- Author
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Robert R, Ang C, Sun G, Juglair L, Lim EX, Mason LJ, Payne NL, Bernard CC, and Mackay CR
- Abstract
The chemokine receptor CCR6 marks subsets of T cells and innate lymphoid cells that produce IL-17 and IL-22, and as such may play a role in the recruitment of these cells to certain inflammatory sites. However, the precise role of CCR6 has been controversial, in part because no effective monoclonal antibody (mAb) inhibitors against this receptor exist for use in mouse models of inflammation. We circumvented this problem using transgenic mice expressing human CCR6 (hCCR6) under control of its native promoter (hCCR6-Tg/mCCR6-/-). We also developed a fully humanized mAb against hCCR6 with antagonistic activity. The expression pattern of hCCR6 in hCCR6-Tg/mCCR6-/- mice was consistent with the pattern observed in humans. In mouse models of experimental autoimmune encephalomyelitis (EAE) and psoriasis, treatment with anti-hCCR6 mAb was remarkably effective in both preventive and therapeutic regimens. For instance, in the imiquimod model of psoriasis, anti-CCR6 completely abolished all signs of inflammation. Moreover, anti-hCCR6 attenuated clinical symptoms of myelin oligodendrocyte glycoprotein-induced (MOG-induced) EAE and reduced infiltration of inflammatory cells in the central nervous system. CCR6 plays a critical role in Th17 type inflammatory reactions, and CCR6 inhibition may offer an alternative approach for the treatment of these lesions.
- Published
- 2017
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13. Translocation and dissemination of commensal bacteria in post-stroke infection.
- Author
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Stanley D, Mason LJ, Mackin KE, Srikhanta YN, Lyras D, Prakash MD, Nurgali K, Venegas A, Hill MD, Moore RJ, and Wong CH
- Subjects
- Adrenergic beta-Antagonists pharmacology, Aged, Aged, 80 and over, Animals, Bacteremia immunology, Bacteremia metabolism, Bacteremia microbiology, Bacterial Infections metabolism, Bacterial Infections microbiology, Blood Culture, Computational Biology, Disease Models, Animal, Enterococcus faecalis, Female, Goblet Cells cytology, Goblet Cells metabolism, Gram-Positive Bacterial Infections metabolism, Gram-Positive Bacterial Infections microbiology, High-Throughput Nucleotide Sequencing, Humans, Infarction, Middle Cerebral Artery immunology, Intestine, Small cytology, Intestine, Small drug effects, Intestine, Small microbiology, Male, Mice, Microbiota genetics, Middle Aged, Permeability drug effects, Pneumonia, Bacterial immunology, Pneumonia, Bacterial metabolism, Pneumonia, Bacterial microbiology, Receptors, Adrenergic, beta metabolism, Sequence Analysis, RNA, Specific Pathogen-Free Organisms, Urinary Tract Infections immunology, Urinary Tract Infections metabolism, Urinary Tract Infections microbiology, Zonula Occludens-1 Protein metabolism, Bacterial Infections immunology, Bacterial Translocation immunology, Gastrointestinal Microbiome genetics, Gram-Positive Bacterial Infections immunology, Intestine, Small metabolism, RNA, Ribosomal, 16S genetics, Stroke immunology
- Abstract
Bacterial infection is highly prevalent in patients who have had a stroke. Despite the potential contribution of micro-aspiration in post-stroke pneumonia, we found that the majority of the microorganisms detected in the patients who developed infections after having a stroke were common commensal bacteria that normally reside in the intestinal tracts. In a mouse model of ischemic stroke, post-stroke infection was only observed in mice that were born and raised in specific-pathogen-free facilities; this was not seen in mice that were born and raised in germ-free facilities. Using high-throughput 16S rRNA gene amplicon sequencing and bioinformatics analyses, we provide evidence demonstrating that the source of the bacteria forming the microbial community in the lungs of post-stroke mice was indeed the host small intestine. Additionally, stroke-induced gut barrier permeability and dysfunction preceded the dissemination of orally inoculated bacteria to peripheral tissues. This study identifies a novel pathway in which stroke promotes the translocation and dissemination of selective strains of bacteria that originated from the host gut microbiota.
- Published
- 2016
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14. G Protein-Coupled Receptor 43 Modulates Neutrophil Recruitment during Acute Inflammation.
- Author
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Kamp ME, Shim R, Nicholls AJ, Oliveira AC, Mason LJ, Binge L, Mackay CR, and Wong CH
- Abstract
Fermentation of dietary fibre in the gut yields large amounts of short chain fatty acids (SCFAs). SCFAs can impart biological responses in cells through their engagement of 'metabolite-sensing' G protein-coupled receptors (GPCRs). One of the main SCFA receptors, GPR43, is highly expressed by neutrophils, which suggests that the actions of GPR43 and dietary fibre intake may affect neutrophil recruitment during inflammatory responses in vivo. Using intravital imaging of the small intestine, we found greater intravascular neutrophil rolling and adhesion in Gpr43-/-mice in response to LPS at 1 h. After 4 h of LPS challenge, the intravascular rolling velocity of GPR43-deficient neutrophils was reduced significantly and increased numbers of neutrophils were found in the lamina propria of Gpr43-/-mice. Additionally, GPR43-deficient leukocytes demonstrated exacerbated migration into the peritoneal cavity following fMLP challenge. The fMLP-induced neutrophil migration was significantly suppressed in wildtype mice that were treated with acetate, but not in Gpr43-/-mice, strongly suggesting a role for SCFAs in modulating neutrophil migration via GPR43. Indeed, neutrophils of no fibre-fed wildtype mice exhibited elevated migratory behaviour compared to normal chow-fed wildtype mice. Interestingly, this elevated migration could also be reproduced through simple transfer of a no fibre microbiota into germ-free mice, suggesting that the composition and function of microbiota stemming from a no fibre diet mediated the changes in neutrophil migration. Therefore, GPR43 and a microbiota composition that allows for SCFA production function to modulate neutrophil recruitment during inflammatory responses., Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2016
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15. Avenues to autoimmune arthritis triggered by diverse remote inflammatory challenges.
- Author
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Chevalier N, Tan JK, Mason LJ, Robert R, McKenzie CI, Lim F, Wong CH, Macia L, Thorburn AN, Russ BE, Masters SL, and Mackay CR
- Subjects
- Adoptive Transfer, Animals, Arthritis, Rheumatoid genetics, Colitis chemically induced, Colitis immunology, Dextran Sulfate toxicity, Genetic Predisposition to Disease, Influenza A virus immunology, Interleukin-17 metabolism, Joints immunology, Klebsiella pneumoniae immunology, Lung Diseases immunology, Lung Diseases virology, Mice, Mice, Inbred C57BL, Mice, Inbred NOD, Mice, Transgenic, Orthomyxoviridae Infections immunology, Orthomyxoviridae Infections virology, Pneumonia, Bacterial immunology, Pneumonia, Bacterial microbiology, Receptors, Interleukin-1 genetics, Receptors, Interleukin-1 metabolism, Th17 Cells metabolism, Arthritis, Experimental immunology, Arthritis, Rheumatoid immunology, CD4-Positive T-Lymphocytes immunology, Cell Differentiation immunology, Interleukin-1beta metabolism, Spondylarthritis immunology, Th17 Cells immunology
- Abstract
Environmental factors contribute to development of autoimmune diseases. For instance, human autoimmune arthritis can associate with intestinal inflammation, cigarette smoking, periodontal disease, and various infections. The cellular and, molecular pathways whereby such remote challenges might precipitate arthritis or flares remain unclear. Here, we used a transfer model of self-reactive arthritis-inducing CD4(+) cells from KRNtg mice that, upon transfer, induce a very mild form of autoinflammatory arthritis in recipient animals. This model enabled us to identify external factors that greatly aggravated disease. We show that several distinct challenges precipitated full-blown arthritis, including intestinal inflammation through DSS-induced colitis, and bronchial stress through Influenza infection. Both triggers induced strong IL-17 expression primarily in self-reactive CD4(+) cells in lymph nodes draining the site of inflammation. Moreover, treatment of mice with IL-1β greatly exacerbated arthritis, while transfer of KRNtg CD4(+) cells lacking IL-1R significantly reduced disease and IL-17 expression. Thus, IL-1β enhances the autoaggressive potential of self-reactive CD4(+) cells, through increased Th17 differentiation, and this influences inflammatory events in the joints. We propose that diverse challenges that cause remote inflammation (lung infection or colitis, etc.) result in IL-1β-driven Th17 differentiation, and this precipitates arthritis in genetically susceptible individuals. Thus the etiology of autoimmune inflammatory arthritis likely relates to diverse triggers that converge to a common pathway involving IL-1β production and Th17 cell distribution., (Copyright © 2016 Elsevier Ltd. All rights reserved.)
- Published
- 2016
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16. The Role of Follicular Helper T Cell Molecules and Environmental Influences in Autoantibody Production and Progression to Inflammatory Arthritis in Mice.
- Author
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Chevalier N, Macia L, Tan JK, Mason LJ, Robert R, Thorburn AN, Wong CH, Tsai LM, Bourne K, Brink R, Yu D, and Mackay CR
- Subjects
- Animals, Arthritis, Psoriatic immunology, Arthritis, Rheumatoid genetics, Autoantibodies immunology, Autoimmune Diseases immunology, Disease Models, Animal, Disease Progression, Enzyme-Linked Immunosorbent Assay, Flow Cytometry, Germinal Center cytology, Glucose-6-Phosphate Isomerase immunology, Intracellular Signaling Peptides and Proteins genetics, Mice, Mice, Knockout, Mice, Transgenic, Real-Time Polymerase Chain Reaction, Receptors, CXCR5 genetics, Reverse Transcriptase Polymerase Chain Reaction, Signaling Lymphocytic Activation Molecule Associated Protein, Arthritis, Rheumatoid immunology, Autoantibodies biosynthesis, Environment, Intracellular Signaling Peptides and Proteins immunology, Receptors, CXCR5 immunology, T-Lymphocytes, Helper-Inducer immunology
- Abstract
Objective: Antibody-mediated autoimmunity involves cognate interactions between self-reactive T cells and B cells during germinal center (GC) reactions. The aim of this study was to determine the role of essential follicular helper T (Tfh) cell molecules (CXCR5, signaling lymphocytic activation molecule-associated protein) on autoreactive CD4+ cells and the role of certain environmental influences that may determine GC-driven autoantibody production and arthritis development., Methods: We transferred self-reactive CD4+ cells from KRN-Tg mice into recipient mice, which induced autoantibodies and autoinflammatory arthritis. This model allowed manipulation of environmental effects, such as inflammation, and use of transferred cells that were genetically deficient in important Tfh cell-associated molecules., Results: A deficiency of signaling lymphocytic activation molecule-associated protein (SAP) in CD4+ cells from KRN-Tg mice completely protected against arthritis, indicating that stable T cell-B cell interactions are required for GC formation, autoantibody production, and arthritis induction. In contrast, a CXCR5 deficiency in CD4+ cells from KRN-Tg mice still induced disease when these cells were transferred into wild-type mice, suggesting that T cell help for B cells could rely on other migration mechanisms. However, various manipulations influenced this system, including elimination of bystander effects through use of CD28(-/-) recipient mice (reduced disease) or use of inflammation-inducing Freund's complete adjuvant (progression to arthritis). We also examined the capacity of preexisting GCs with a nonautoimmune specificity to co-opt autoimmune T cells and observed no evidence for any influence., Conclusion: In addition to the quality and quantity of cognate CD4+ cell help, external factors such as inflammation and noncognate CD4+ cell bystander activation trigger autoimmunity by shaping events within autoimmune GC responses. SAP is an essential molecule for autoimmune antibody production, whereas the importance of CXCR5 varies depending on the circumstances., (© 2016, American College of Rheumatology.)
- Published
- 2016
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17. Evidence that asthma is a developmental origin disease influenced by maternal diet and bacterial metabolites.
- Author
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Thorburn AN, McKenzie CI, Shen S, Stanley D, Macia L, Mason LJ, Roberts LK, Wong CH, Shim R, Robert R, Chevalier N, Tan JK, Mariño E, Moore RJ, Wong L, McConville MJ, Tull DL, Wood LG, Murphy VE, Mattes J, Gibson PG, and Mackay CR
- Subjects
- Acetates pharmacology, Acetylation drug effects, Animals, Asthma immunology, Disease Models, Animal, Epigenesis, Genetic drug effects, Fatty Acids, Volatile metabolism, Fatty Acids, Volatile pharmacology, Female, Forkhead Transcription Factors drug effects, Forkhead Transcription Factors genetics, Histone Deacetylases drug effects, Histone Deacetylases metabolism, Mice, Pregnancy, Prenatal Exposure Delayed Effects immunology, Promoter Regions, Genetic, Repressor Proteins drug effects, Repressor Proteins metabolism, T-Lymphocytes, Regulatory cytology, T-Lymphocytes, Regulatory drug effects, Acetates metabolism, Asthma metabolism, Diet, Dietary Fiber metabolism, Gastrointestinal Microbiome, Prenatal Exposure Delayed Effects metabolism, T-Lymphocytes, Regulatory immunology
- Abstract
Asthma is prevalent in Western countries, and recent explanations have evoked the actions of the gut microbiota. Here we show that feeding mice a high-fibre diet yields a distinctive gut microbiota, which increases the levels of the short-chain fatty acid, acetate. High-fibre or acetate-feeding led to marked suppression of allergic airways disease (AAD, a model for human asthma), by enhancing T-regulatory cell numbers and function. Acetate increases acetylation at the Foxp3 promoter, likely through HDAC9 inhibition. Epigenetic effects of fibre/acetate in adult mice led us to examine the influence of maternal intake of fibre/acetate. High-fibre/acetate feeding of pregnant mice imparts on their adult offspring an inability to develop robust AAD. High fibre/acetate suppresses expression of certain genes in the mouse fetal lung linked to both human asthma and mouse AAD. Thus, diet acting on the gut microbiota profoundly influences airway responses, and may represent an approach to prevent asthma, including during pregnancy.
- Published
- 2015
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18. Challenges in paediatric ambulatory anesthesia.
- Author
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Hanna AH and Mason LJ
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- Child, Child, Preschool, Fasting, Humans, Infant, Infant, Newborn, Postoperative Care, Preoperative Care, Sleep Apnea, Obstructive complications, Sleep Apnea, Obstructive diagnosis, Ambulatory Surgical Procedures, Anesthesia, Pediatrics
- Abstract
Purpose of Review: Clinical studies and new guidelines are frequently being published in the area of preoperative fasting. A growing population of patients with obstructive sleep apnea is being referred for outpatient procedures including adenotonsillectomy., Recent Findings: Recently published preoperative fasting guidelines for pediatric patients are covered along with studies comparing gastric volume following different fasting intervals. Pediatric obstructive sleep apnea is discussed. Clinical presentation, severity, perioperative risks, and controversies as whether outpatient procedures are suitable for these patients are presented. New data covering different perioperative aspects are presented., Summary: A more liberal preoperative intake is encouraged with fasting for 2 h for clear liquids, 4 h for breast milk, 6 h for formula and light meals, and 8 h for heavy meals is widely accepted. Interpersonal variation in residual gastric volume exists. Children with obstructive sleep apnea under 3 years of age and those with severe obstructive sleep apnea and comorbidities are not candidates for ambulatory surgery. Polysomnography has specific preoperative indications. Dexmedetomidine can decrease emergence agitation and has an opioid-sparing effect. Intravenous acetaminophen is presented as an opioid-sparing analgesic. Dexamethasone is effective in preventing postoperative nausea without increased risk of bleeding. Surgical techniques may affect postoperative pain.
- Published
- 2012
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19. Culturing and investigation of stress-induced lipid accumulation in microalgae using a microfluidic device.
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Holcomb RE, Mason LJ, Reardon KF, Cropek DM, and Henry CS
- Subjects
- Biofuels, Lipid Metabolism, Microalgae metabolism, Microfluidics instrumentation
- Abstract
There is increasing interest in using microalgae as a lipid feedstock for the production of biofuels. Lipids used for these purposes are triacylglycerols that can be converted to fatty acid methyl esters (biodiesel) or decarboxylated to "green diesel." Lipid accumulation in most microalgal species is dependent on environmental stress and culturing conditions, and these conditions are currently optimized using slow, labor-intensive screening processes. Increasing the screening throughput would help reduce the development cost and time to commercial production. Here, we demonstrated an initial step towards this goal in the development of a glass/poly(dimethylsiloxane) (PDMS) microfluidic device capable of screening microalgal culturing and stress conditions. The device contained power-free valves to isolate microalgae in a microfluidic growth chamber for culturing and stress experiments. Initial experiments involved determining the biocompatibility and culturing capability of the device using the microalga Tetraselmis chuii. With this device, T. chuii could be successfully cultured for up to 3 weeks on-chip. Following these experiments, the device was used to investigate lipid accumulation in the microalga Neochloris oleabundans. It was shown that this microalga could be stressed to accumulate cytosolic lipids in a microfluidic environment, as evidenced with fluorescence lipid staining. This work represents the first example of microalgal culturing in a microfluidic device and signifies an important expansion of microfluidics into the biofuels research arena.
- Published
- 2011
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20. Economics of integrated insect management in stored corn.
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Yigezu YA, Alexander CE, Preckel PV, Maier DE, Mason LJ, Woloshuk C, Lawrence J, and Moog DJ
- Subjects
- Agriculture economics, Agriculture methods, Costs and Cost Analysis, Insect Control methods, Population Growth, United States, Insect Control economics, Zea mays parasitology
- Abstract
Insects can cause substantial damage to stored grain. In addition, consumers and therefore food processors are increasingly interested in chemical-free products. Integrated pest management (IPM) may increase farmers' profits while reducing their use of pesticides. This study uses a stochastic dynamic programming framework to model the economics of optimal insect control in corn, Zea mays L., stored on-farm with multiple controls conditional on the biophysical conditions of the grain in the bin. We find that for farmers who have a contract with a food processor, where there are quality premiums, the optimal management strategy depends on monitoring the biophysical conditions of the grain and the time period under consideration. For farmers who deliver to the commodity market, their current practices are optimal.
- Published
- 2010
- Full Text
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21. Relationship between anti-dsDNA, anti-nucleosome and anti-alpha-actinin antibodies and markers of renal disease in patients with lupus nephritis: a prospective longitudinal study.
- Author
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Manson JJ, Ma A, Rogers P, Mason LJ, Berden JH, van der Vlag J, D'Cruz DP, Isenberg DA, and Rahman A
- Subjects
- Adolescent, Adult, Antibodies, Antinuclear blood, Autoantibodies immunology, Biomarkers analysis, Biomarkers blood, DNA immunology, Enzyme-Linked Immunosorbent Assay, Female, Humans, Immunoglobulin G blood, Immunoglobulin G immunology, Kidney Function Tests, Longitudinal Studies, Lupus Nephritis immunology, Male, Middle Aged, Young Adult, Actinin immunology, Antibodies, Antinuclear immunology, Autoantibodies blood, Lupus Nephritis blood, Nucleosomes immunology
- Abstract
Introduction: Glomerulonephritis is a major cause of morbidity and mortality in patients with systemic lupus erythematosus (SLE). Deposition of autoantibodies in the glomeruli plays a key role in the development of lupus nephritis (LN). Different groups have proposed that either anti-nucleosome antibodies or antibodies that bind the intrinsic renal antigen, alpha-actinin, are central to the pathogenesis of LN. These theories have been based mainly on cross-sectional studies in patients and on experiments in animal models. No previous longitudinal studies have compared the relationships between levels of these antibodies and markers of renal function. We assessed how well anti-alpha-actinin, anti-nucleosome and anti-double-stranded DNA (anti-dsDNA) antibodies reflected renal outcome measures in patients with new-onset LN followed for up to 2 years., Methods: Renal disease activity was monitored by measuring urine protein/creatinine ratio (PCR), serum albumin and a composite outcome of renal remission. At each time point, anti-nucleosome and anti-alpha-actinin antibodies were measured by enzyme-linked immunosorbent assay. High-avidity anti-dsDNA antibodies were measured using the Farrzyme assay. We analysed relationships between levels of the three antibodies and between antibody levels and renal outcome measures over time., Results: Levels of anti-nucleosome and anti-dsDNA were positively correlated with each other (r = 0.6, P = 0.0001) but neither correlated with anti-alpha-actinin level. At baseline, mean anti-nucleosome levels were higher in patients with LN than in healthy controls (0.32 versus 0.01, P < 0.001). The same was true for anti-dsDNA antibodies (0.50 versus 0.07, P < 0.001) but not for anti-alpha-actinin (0.33 versus 0.29). Over the follow-up period, anti-nucleosome and anti-dsDNA levels associated positively with urine PCR (P = 0.041 and 0.051, respectively) and negatively with serum albumin (P = 0.027 and 0.032, respectively). Both anti-nucleosome and anti-dsDNA levels were significantly lower during renal remission than when renal disease was active (P = 0.002 and 0.003, respectively). However, there was no relationship between anti-alpha-actinin levels and urine PCR, serum albumin or remission status., Conclusions: This prospective longitudinal clinical study is the first to compare levels of anti-nucleosome, anti-dsDNA and anti-alpha-actinin antibodies in the same patients with SLE. Our results support the concept that, in the majority of patients, anti-nucleosome antibodies play a major role in pathogenesis of LN, in contrast to anti-alpha-actinin antibodies.
- Published
- 2009
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22. Airway management in two of newborns with Pierre Robin Sequence: the use of disposable vs multiple use LMA for fiberoptic intubation.
- Author
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Cain JM, Mason LJ, and Martin RD
- Subjects
- Cleft Palate surgery, Female, Fiber Optic Technology methods, Humans, Infant, Infant, Newborn, Laryngeal Masks adverse effects, Laryngeal Masks standards, Laryngoscopy methods, Disposable Equipment, Intubation, Intratracheal methods, Pierre Robin Syndrome therapy
- Abstract
In this article, we discuss the use of LMAs as a conduit to intubate the trachea of two Pierre Robin Sequence infants. Multiple use LMAs will admit larger diameter tracheal tubes (TT) than their disposable counterparts. Increased friction with the surface of the TT makes passing even small diameter tubes through the lumen of the disposable LMA difficult.
- Published
- 2006
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23. Antiphospholipid antibodies are associated with enhanced oxidative stress, decreased plasma nitric oxide and paraoxonase activity in an experimental mouse model.
- Author
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Delgado Alves J, Mason LJ, Ames PR, Chen PP, Rauch J, Levine JS, Subang R, and Isenberg DA
- Subjects
- Animals, Antiphospholipid Syndrome blood, Antiphospholipid Syndrome immunology, Disease Models, Animal, Enzyme-Linked Immunosorbent Assay methods, Female, Humans, Immunoglobulin G blood, Immunoglobulin M blood, Kidney enzymology, Mice, Mice, Inbred BALB C, Mice, SCID, Nitric Oxide Synthase blood, Nitric Oxide Synthase Type II, Nitric Oxide Synthase Type III, Antibodies, Antiphospholipid blood, Antiphospholipid Syndrome physiopathology, Aryldialkylphosphatase blood, Nitric Oxide blood, Oxidative Stress immunology
- Abstract
Objective: Oxidative stress contributes to atherosclerosis, and evidence of enhanced oxidative stress exists in antiphospholipid syndrome (APS). In a non-lupus murine model, we evaluated whether anticardiolipin (aCL) antibodies could affect the oxidant/antioxidant balance as an early biochemical step of APS., Methods: Hybridomas producing human and murine aCL and anti-beta(2)-glycoprotein I (abeta2-GPI) monoclonal antibodies were injected into three groups of five female BALB/c severe combined immunodeficiency (SCID) mice. Corresponding hybridomas secreting non-antiphospholipid antibodies of the same isotype were employed as controls. Sera and organs were collected after 30 days. Paraoxonase (PON) activity, peroxynitrite, superoxide, nitric oxide (NO) and nitrotyrosine were measured in plasma. Expression of endothelial nitric oxide synthase and inducible nitric oxide synthase (iNOS) was assessed by western blot and immunohistochemistry., Results: PON activity and NO (sum of nitrate and nitrite) levels were reduced in the human aCL IgG group (P<0.002 and P<0.04, respectively), whilst peroxynitrite and superoxide and expression of total antioxidant capacity of plasma were increased (P<0.01). PON and NO were decreased in the murine abeta2-GPI IgG and IgM aCL groups (P<0.03 and P<0.05, respectively). Nitrotyrosine was elevated in the human aCL IgG group (P<0.03). Western blotting showed reduced iNOS expression in the hearts of the IgG aCL group, confirmed by immunostaining. PON inversely correlated with IgG aCL titres (P<0.001), superoxide (P<0.008) and peroxynitrite levels (P<0.0009). Peroxynitrite and total IgG aCL were independent predictors of PON (P<0.0009 and P<0.02, respectively). Superoxide was the only independent predictor of NO (P<0.008) and of nitrotyrosine (P<0.002)., Conclusion: aCL antibodies are associated with the decreased PON activity and reduced NO that may occur in the preclinical phase of APS.
- Published
- 2005
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24. Stable expression of a recombinant human antinucleosome antibody to investigate relationships between antibody sequence, binding properties, and pathogenicity.
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Mason LJ, Lambrianides A, Haley JD, Manson JJ, Latchman DS, Isenberg DA, and Rahman A
- Subjects
- Animals, Antibodies, Antinuclear biosynthesis, Antibodies, Antinuclear genetics, Antibody Specificity, Antigen-Antibody Reactions, CHO Cells immunology, CHO Cells transplantation, Cell Line, Cricetinae, Cricetulus, Culture Media, Conditioned pharmacology, DNA immunology, Disease Models, Animal, Female, Humans, Immunoglobulin Heavy Chains genetics, Immunoglobulin Heavy Chains immunology, Immunoglobulin Light Chains genetics, Immunoglobulin Light Chains immunology, Kidney immunology, Kidney pathology, Lupus Nephritis immunology, Mice, Mice, Inbred BALB C, Mice, SCID, Proteinuria immunology, Proteinuria pathology, Recombinant Fusion Proteins biosynthesis, Recombinant Fusion Proteins genetics, Recombinant Fusion Proteins immunology, Transfection, Antibodies, Antinuclear immunology, Nucleosomes immunology, Proteinuria etiology
- Abstract
When purified under rigorous conditions, some murine anti-double-stranded-DNA (anti-dsDNA) antibodies actually bind chromatin rather than dsDNA. This suggests that they may actually be antinucleosome antibodies that only appear to bind dsDNA when they are incompletely dissociated from nucleosomes. Experiments in murine models suggest that antibody-nucleosome complexes may play a crucial role in the pathogenesis of glomerulonephritis in systemic lupus erythematosus. Some human monoclonal anti-DNA antibodies are pathogenic when administered to mice with severe combined immunodeficiency (SCID). Our objective was to achieve stable expression of sequence-altered variants of one such antibody, B3, in Chinese hamster ovary (CHO) cells. Purified antibodies secreted by these cells were tested to investigate whether B3 is actually an antinucleosome antibody. The pathogenic effects of the antibodies were tested by implanting CHO cells secreting them into SCID mice. Purified B3 does not bind to dsDNA unless supernatant from cultured cells is added, but does bind to nucleosomes. The strength of binding to dsDNA and nucleosomes is dependent on the sequence of the light chain. Mice that received CHO cells secreting wild-type B3 developed more proteinuria and died earlier than control mice that received nonsecreting CHO cells or mice that received B3 with a single light chain mutation. However, none of the mice had histological changes or deposition of human immunoglobulin G in the kidneys. Sequence changes may alter the pathogenicity of B3, but further studies using different techniques are needed to investigate this possibility.
- Published
- 2005
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25. An update on the etiology and prevention of anesthesia-related cardiac arrest in children.
- Author
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Mason LJ
- Subjects
- Child, Child, Preschool, Heart Arrest classification, Humans, Infant, Anesthesia adverse effects, Heart Arrest etiology, Heart Arrest prevention & control
- Published
- 2004
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- View/download PDF
26. Is alpha-actinin a target for pathogenic anti-DNA antibodies in lupus nephritis?
- Author
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Mason LJ, Ravirajan CT, Rahman A, Putterman C, and Isenberg DA
- Subjects
- Cross Reactions, Enzyme-Linked Immunosorbent Assay, Humans, Immunoglobulin G immunology, Lupus Erythematosus, Systemic immunology, Actinin immunology, Antibodies, Antinuclear immunology, Antibodies, Monoclonal immunology, Lupus Nephritis immunology
- Abstract
Objective: Following recent reports that pathogenic murine anti-DNA antibodies bind to alpha-actinin, it was obviously of interest to assess the ability of human pathogenic anti-double-stranded DNA (anti-dsDNA) antibodies to bind this antigen. Both human monoclonal anti-DNA antibodies and antibodies affinity purified from the sera of patients with systemic lupus erythematosus (SLE) were investigated., Methods: An enzyme-linked immunosorbent assay was established to measure immunoglobulin binding to alpha-actinin. Antibodies binding dsDNA were purified from the sera of SLE patients who either had active renal disease or had never had renal disease. Serum samples were selected at times when the patients' sera exhibited high IgG binding to dsDNA. The binding of supernatants from 3 high-affinity human anti-dsDNA IgG hybridomas (RH14, B3, and DIL-6) and 7 human IgM anti-DNA hybridomas was also investigated., Results: A greater proportion of anti-dsDNA IgG-binding antibodies purified from patients with renal disease bound to alpha-actinin than did those purified from the sera of patients without renal disease. The specificity of binding to the 100-kd alpha-actinin molecule was confirmed by Western blotting. The pathogenic human antibodies RH14 and B3 bound strongly to alpha-actinin, while nonpathogenic DIL-6 bound very weakly. RT84, the IgM antibody that binds dsDNA with the highest affinity, exhibited the greatest binding to alpha-actinin., Conclusion: The results of our study support the findings of previous studies using murine anti-DNA monoclonal antibodies, which suggest that pathogenic anti-dsDNA antibodies cross-react with alpha-actinin.
- Published
- 2004
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27. Somatic mutations to arginine residues affect the binding of human monoclonal antibodies to DNA, histones, SmD and Ro antigen.
- Author
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Haley J, Mason LJ, Nagl S, Giles I, Latchman DS, Isenberg DA, and Rahman A
- Subjects
- Amino Acid Sequence, Animals, Antibodies, Monoclonal immunology, Antibodies, Monoclonal metabolism, Arginine metabolism, Binding Sites, Antibody genetics, Binding Sites, Antibody immunology, COS Cells, Enzyme-Linked Immunosorbent Assay, Gene Transfer Techniques, Humans, Molecular Sequence Data, Protein Structure, Tertiary, snRNP Core Proteins, Antibodies, Monoclonal genetics, Arginine genetics, Autoantigens, DNA immunology, Histones immunology, RNA, Small Cytoplasmic, Ribonucleoproteins immunology, Ribonucleoproteins, Small Nuclear immunology
- Abstract
Autoantibodies to a wide variety of antigens are associated with systemic lupus erythematosus (SLE). Antibodies to double-stranded DNA (anti-dsDNA) are thought to be particularly closely related to tissue damage and disease activity in SLE. Autoantibodies to histones, Sm and Ro are found in patients with SLE, but their role in pathogenesis is unclear. Using a transient expression system, we previously showed that particular sequence motifs in CDRs of light chains derived from the human Vlambda gene 2a2 are very important in determining their ability to form a DNA-binding site, when paired with the heavy chain of the human monoclonal anti-dsDNA antibody B3. These motifs are often sites of somatic mutation and/or contain arginine residues. In the experiments reported in this paper, the same expression system was used to show that these CDR motifs also affect binding to histones, Ro antigen and Sm antigen, but that binding to different antigens is affected in diverse ways by particular changes in the sequence of the CDRs. The heavy chain also plays a role in binding to these antigens. Pairing of the same range of 11 2a2 derived light chains with the heavy chain of a different anti-DNA antibody, 33.H11, gave reduced ability to bind DNA in comparison with the results obtained using the B3 heavy chain. Computer-generated models of the three-dimensional structures of these heavy/light chain combinations were used to define the positions occupied by the important sequence motifs at the binding sites of these antibodies, and to explain the different effects exerted by arginine residues at different positions in the light chains.
- Published
- 2004
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28. Efficacy and fumigation characteristics of ozone in stored maize.
- Author
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Kells SA, Mason LJ, Maier DE, and Woloshuk CP
- Abstract
This study evaluated the efficacy of ozone as a fumigant to disinfest stored maize. Treatment of 8.9tonnes (350bu) of maize with 50ppm ozone for 3d resulted in 92-100% mortality of adult red flour beetle, Tribolium castaneum (Herbst), adult maize weevil, Sitophilus zeamais (Motsch.), and larval Indian meal moth, Plodia interpunctella (Hübner) and reduced by 63% the contamination level of the fungus Aspergillus parasiticus Speare on the kernel surface. Ozone fumigation of maize had two distinct phases. Phase 1 was characterized by rapid degradation of the ozone and slow movement through the grain. In Phase 2, the ozone flowed freely through the grain with little degradation and occurred once the molecular sites responsible for ozone degradation became saturated. The rate of saturation depended on the velocity of the ozone/air stream. The optimum apparent velocity for deep penetration of ozone into the grain mass was 0.03m/s, a velocity that is achievable in typical storage structures with current fans and motors. At this velocity 85% of the ozone penetrated 2.7m into the column of grain in 0.8d during Phase 1 and within 5d a stable degradation rate of 1ppm/0.3m was achieved. Optimum velocity for Phase 2 was 0.02m/s. At this velocity, 90% of the ozone dose penetrated 2.7m in less than 0.5d. These data demonstrate the potential usefulness of using ozone in managing stored maize and possibly other grains.
- Published
- 2001
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29. A human anti-dsDNA monoclonal antibody caused hyaline thrombi formation in kidneys of 'leaky' SCID mice.
- Author
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Mason LJ, Ravirajan CT, Latchman DS, and Isenberg DA
- Subjects
- Animals, Humans, Hyalin cytology, Hybridomas, Lupus Erythematosus, Systemic pathology, Mice, Mice, Inbred BALB C, Mice, SCID, Antibodies, Antinuclear pharmacology, Antibodies, Monoclonal pharmacology, DNA immunology, Kidney pathology, Lupus Erythematosus, Systemic etiology, Thrombosis pathology
- Abstract
There are few studies assessing the pathogenicity of human monoclonal anti-DNA antibodies. The use of SCID mice avoids the problem of rejection of the human hybridoma cells thus allowing in vivo assessment of human immunoglobulins. Using electron microscopy we have shown that the human IgG anti-dsDNA monoclonal antibody, RH14, is nephritogenic in SCID mice, causing morphological changes in the kidney due to immunoglobulin deposition. The problem with using SCID mice is that they have an abnormal immune system; normally they are used at about 2 months of age, at which time they have virtually no functional T or B cells. It is known that older SCID mice become increasingly 'leaky', that is they develop some mature lymphocyte clones. Our aim was to assess if implanting anti-DNA antibodies into older 'leaky' SCID mice would result in pathology which was observable by light microscopy. Eight-month-old SCID mice were implanted with human hybridoma cells secreting either RH14 an anti-dsDNA IgG, CL24, an antiphospholipid antibody or an irrelevant human IgG control. As previously, RH14 deposited in the kidney and caused proteinuria but unexpectedly we also observed hyaline thrombi in the kidney glomeruli and peritubular capillaries. These thrombi occurred only in the case of RH14 implanted mice and were found to stain positively for human IgG and fibrin. However, apart from the interesting thrombi, we did not observe any greater pathological damage resulting from the anti-dsDNA antibody deposition than we had seen in the younger mice; indeed, the electron microscopic findings were more limited.
- Published
- 2001
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30. Pediatric cardiac emergencies.
- Author
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Lee C and Mason LJ
- Subjects
- Child, Humans, Anesthesia, Emergency Medical Services, Heart Diseases therapy
- Abstract
Successful management of pediatric cardiac emergencies requires an accurate diagnosis to institute an appropriate plan of therapy. The diagnosis, however, is not always straightforward, as evidenced by the nonspecific clinical picture that can be presented by congenital heart defects. Entertaining the possibility of a cardiac problem in neonates with pulmonary symptoms unresponsive to standard therapies is crucial for successful management of patients with congenital heart disease. In addition to ventilatory support, prostaglandin E1 infusions or emergency interventional cardiac catheterization is often a life-saving initial measure in patients with acutely decompensated congenital cardiac lesions that require a patent ductus arteriosus for survival. Pericardial tamponade is associated with various acquired and iatrogenic causes. Emergent pericardiocentesis is mandatory when cardiovascular compromise occurs. The goal of anesthetic management is to maintain cardiac output. With the increasing use of central venous catheters in neonatal ICUs and the high mortality rate for central venous catheter-related cardiac tamponade, the diagnosis must be considered in any patient with a central venous catheter in situ who acutely develops unexplained hypotension, bradycardia, and diminished pulses. Arrhythmias also can cause hemodynamic instability in infants and children. Supraventricular tachycardia is by far the most common emergently presenting arrhythmia in the pediatric population. Unstable patients require immediate intravenous adenosine or synchronized cardioversion. Complete heart block is rare, but it can lead to congestive heart failure and occasionally to cardiovascular collapse and sudden death. Emergency treatment of complete heart block includes pharmacologic support and temporary or permanent pacemaker placement as indicated. In infants, congestive heart failure usually is related to congenital heart disease, whereas in older children, it tends to be secondary to an acquired cause. Supportive measures, fluid restriction, and inotropic support are the principles of initial treatment. Prompt recognition and initiation of appropriate therapy in pediatric cardiac emergencies are essential for favorable outcomes.
- Published
- 2001
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31. A comparative study into the mechanisms of action of anti-tumor necrosis factor alpha, anti-CD4, and combined anti-tumor necrosis factor alpha/anti-CD4 treatment in early collagen-induced arthritis.
- Author
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Marinova-Mutafchieva L, Williams RO, Mauri C, Mason LJ, Walmsley MJ, Taylor PC, Feldmann M, and Maini RN
- Subjects
- Animals, Arthritis, Rheumatoid chemically induced, Arthritis, Rheumatoid metabolism, Collagen immunology, Drug Therapy, Combination, Immunohistochemistry, Inguinal Canal, Integrin alpha4beta1, Integrins biosynthesis, Interferon-gamma drug effects, Interferon-gamma metabolism, Joints chemistry, Lymph Nodes cytology, Lymph Nodes metabolism, Male, Mice, Mice, Inbred DBA, Receptors, Lymphocyte Homing biosynthesis, Vascular Cell Adhesion Molecule-1 biosynthesis, Antibodies physiology, Antibodies therapeutic use, Arthritis, Rheumatoid drug therapy, CD4 Antigens immunology, Tumor Necrosis Factor-alpha immunology
- Abstract
Objective: Anti-tumor necrosis factor alpha (anti-TNFalpha) therapy is very effective in rheumatoid arthritis (RA), whereas depleting anti-CD4 therapy is relatively ineffective. To explain the differences in efficacy between these 2 therapies, we used an animal model of RA to compare their effects on different aspects of the disease process., Methods: Mice with collagen-induced arthritis were treated with depleting anti-CD4 monoclonal antibodies (mAb), anti-TNFalpha mAb, or phosphate buffered saline. Another group was given a combination of anti-TNFalpha plus anti-CD4. The treatments were compared for their ability to down-regulate the expression of proinflammatory cytokines and adhesion molecules, reduce the cellularity of the joint, and inhibit Th1 activity., Results: Anti-TNFalpha significantly reduced the numbers of cells expressing TNFalpha, interleukin-1beta (IL-1beta), very late activation antigen 4 (VLA-4), vascular cell adhesion molecule 1 (VCAM-1), and numbers of CD4+ T cells and macrophages in the joint. Anti-CD4 treatment led to a small reduction in the expression of TNFalpha, IL-1beta, VLA-4, and VCAM-1, but this did not reach statistical significance. Depleting anti-CD4 was also surprisingly ineffective in eliminating CD4+ T cells from the joint. Anti-TNFalpha therapy was also more effective than anti-CD4 in reducing Thl activity, as assessed by the production of interferon-gamma in lymph node cell cultures. There was a synergistic relationship between anti-TNFalpha and anti-CD4 in the reduction of histologic score and inhibition of TNFalpha/IL-1beta expression in the joints., Conclusion: The efficacy of the 3 treatments correlated with their ability to modulate the expression of inflammatory cytokines and adhesion molecules in the joint, reduce the cellularity of the joint, and inhibit Th1 activity. This kind of analysis may prove useful in the testing of novel therapies for RA.
- Published
- 2000
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32. Immunization with a peptide of Sm B/B' results in limited epitope spreading but not autoimmune disease.
- Author
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Mason LJ, Timothy LM, Isenberg DA, and Kalsi JK
- Subjects
- Animals, Autoantibodies biosynthesis, Autoantigens administration & dosage, Autoantigens metabolism, Disease Models, Animal, Epitopes, B-Lymphocyte administration & dosage, Female, Immunization, Secondary, Immunoglobulin G biosynthesis, Injections, Intraperitoneal, Injections, Intravenous, Injections, Subcutaneous, Lupus Erythematosus, Systemic pathology, Mice, Mice, Inbred A, Mice, Inbred C57BL, Mice, Inbred MRL lpr, Oligopeptides administration & dosage, Oligopeptides metabolism, Rabbits, snRNP Core Proteins, Autoantigens immunology, Epitopes, B-Lymphocyte metabolism, Lupus Erythematosus, Systemic etiology, Lupus Erythematosus, Systemic immunology, Oligopeptides immunology, Ribonucleoproteins, Small Nuclear
- Abstract
An experimental model of systemic lupus erythematosus has recently been described in normal animals. We sought to confirm and extend this model, which involved immunization of normal rabbits and mice with a peptide of Sm B/B', PPPGMRPP. This peptide is an early target of the immune response in anti-Sm-positive patients with lupus. The peptide was used in a multiple Ag peptide format, with multiple copies of PPPGMRPP bound to an inert lysine backbone. New Zealand White rabbits and A/J and C57BL/10ScSn mouse strains were immunized with PPPGMRPP-MAP. Pepscan assays were used to determine the epitope spreading of the anti-PPPGMRPP-MAP response to other octamers of SmB/B' following immunization. We obtained high titer anti-PPPGMRPP-MAP IgG responses in the New Zealand White rabbits and A/J mice. The rabbits immunized with PPPGMRPP-MAP showed varying degrees of epitope spreading, while the A/J mice showed no spreading. We observed no autoantibodies to dsDNA or other anti-nuclear autoantibodies in our animals by ELISA or immunofluorescence, although anti-nuclear autoantibodies were found by Western blotting in some of the rabbits. No evidence of clinical disease was seen in our normal animals. These data underline the difficulties often associated with the reproduction of animal models in different laboratories.
- Published
- 1999
33. Therapeutic actions of cyclosporine and anti-tumor necrosis factor alpha in collagen-induced arthritis and the effect of combination therapy.
- Author
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Williams RO, Mauri C, Mason LJ, Marinova-Mutafchieva L, Ross SE, Feldmann M, and Maini RN
- Subjects
- Animals, Arthritis, Experimental immunology, Dose-Response Relationship, Drug, Drug Therapy, Combination, Male, Mice, Mice, Inbred DBA, Th1 Cells drug effects, Th1 Cells immunology, Tumor Necrosis Factor-alpha immunology, Antibodies, Monoclonal therapeutic use, Arthritis, Experimental drug therapy, Collagen immunology, Cyclosporine therapeutic use
- Abstract
Objective: To define the mechanisms of action of 2 novel drugs, cyclosporine and anti-tumor necrosis factor alpha (TNFalpha), in collagen-induced arthritis and to determine the effect of combination therapy., Methods: Type II collagen-immunized DBA/1 mice with established arthritis were treated with cyclosporine alone, anti-TNFalpha alone, cyclosporine plus anti-TNFalpha, or saline., Results: Cyclosporine was found to ameliorate arthritis, suppress interferon-gamma (IFNgamma) production by CD4+ T cells, and reduce TNFalpha expression in arthritic joints. However, cyclosporine did not directly inhibit TNFalpha production by macrophages, indicating that the decrease in TNFalpha expression observed in vivo was probably an indirect consequence of the reduction in type 1 T helper cell activity. Anti-TNFalpha also reduced IFNgamma production by T cells, indicating that TNFalpha is involved in the cellular immune response to collagen. Combined treatment with cyclosporine plus anti-TNFalpha had an additive therapeutic effect., Conclusion: Although cyclosporine and anti-TNFalpha target different points in the inflammatory pathway, there is an overlap in the consequences of their actions in vivo.
- Published
- 1998
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34. Immunopathogenesis of SLE.
- Author
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Mason LJ and Isenberg DA
- Subjects
- Humans, Autoantibodies immunology, Lupus Erythematosus, Systemic etiology, Lupus Erythematosus, Systemic immunology
- Abstract
Systemic lupus erythematosus (SLE) is an autoimmune rheumatic disease characterized by the deposition of autoantibodies and immune complexes, leading to tissue damage. The immunopathogenesis of SLE is like a jigsaw puzzle, some pieces of which are missing or have not fallen into place. In predisposed individuals, the initial stimulus is likely to be one or more of the environmental agents interacting with susceptibility genes. Once the critical threshold is breached there is a failure of the immune system to downregulate the ensuing abnormal immune response, involving polyclonal B cell activation and hyperactive T cell help. Key questions include, what are the processes behind the availability of autoantigens and the breakdown of tolerance that give rise to the pathogenic autoantibodies? Current areas of research also involve the roles played by cytokines, adhesion molecules, co-stimulatory molecules and apoptosis.
- Published
- 1998
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35. Suppression of TNF-alpha expression, inhibition of Th1 activity, and amelioration of collagen-induced arthritis by rolipram.
- Author
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Ross SE, Williams RO, Mason LJ, Mauri C, Marinova-Mutafchieva L, Malfait AM, Maini RN, and Feldmann M
- Subjects
- Animals, Anti-Inflammatory Agents, Non-Steroidal pharmacology, Antibodies, Monoclonal therapeutic use, Arthritis drug therapy, CD4 Antigens immunology, Cattle, Cytokines biosynthesis, Down-Regulation drug effects, Down-Regulation immunology, Drug Therapy, Combination, Interleukin-12 antagonists & inhibitors, Interleukin-12 biosynthesis, Male, Mice, Mice, Inbred DBA, Pyrrolidinones therapeutic use, Rolipram, Th1 Cells drug effects, Th1 Cells metabolism, Tumor Necrosis Factor-alpha antagonists & inhibitors, Tumor Necrosis Factor-alpha immunology, Arthritis immunology, Collagen immunology, Immunosuppressive Agents pharmacology, Pyrrolidinones pharmacology, Th1 Cells immunology, Tumor Necrosis Factor-alpha biosynthesis
- Abstract
Rolipram is a type IV phosphodiesterase inhibitor that suppresses inflammation and TNF-alpha production. As anti-TNF-alpha therapy is effective in rheumatoid arthritis, we investigated the effect of rolipram on collagen-induced arthritis (CIA), a murine model of rheumatoid arthritis. Rolipram was administered after the onset of clinical arthritis at doses of 0.5, 3, 5, or 10 mg/kg twice daily, with a dose-dependent therapeutic effect on clinical severity and joint erosion. Immunohistochemical analysis of joints of rolipram-treated mice revealed 67% reduction in TNF-alpha-expressing cells compared with control arthritic mice. In vitro studies using bone marrow-derived macrophages confirmed that rolipram directly suppressed TNF-alpha and IL-12 production following stimulation with IFN-gamma and LPS. The effect of rolipram on T cell activity was studied by measuring Th1/Th2 cytokine production by collagen-stimulated draining lymph node cells from arthritic mice treated in vivo with rolipram. Rolipram reduced IFN-gamma production and increased IL-10, indicating that rolipram down-regulated the ongoing Th1 response to type II collagen. Finally, the effect on CIA of combination therapy was studied using rolipram plus either anti-TNF-alpha or anti-CD4 mAbs. Rolipram plus anti-TNF-alpha was not therapeutically additive, whereas rolipram plus anti-CD4 mAb was clearly additive. This result indicates that the therapeutic effects of rolipram overlap with TNF-alpha blockade, but are complementary to anti-CD4 treatment. It is therefore proposed that a major mechanism of action of rolipram in CIA is suppression of TNF-alpha activity. These findings suggest that type IV phosphodiesterase inhibitors may be effective in pathologic conditions, such as RA, with overexpression of TNF-alpha.
- Published
- 1997
36. DBA/1 mice expressing the human TNF-alpha transgene develop a severe, erosive arthritis: characterization of the cytokine cascade and cellular composition.
- Author
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Butler DM, Malfait AM, Mason LJ, Warden PJ, Kollias G, Maini RN, Feldmann M, and Brennan FM
- Subjects
- Animals, Disease Models, Animal, Gene Expression, Gene Transfer Techniques, Humans, Mice, Mice, Inbred DBA, Tumor Necrosis Factor-alpha immunology, Arthritis immunology, Arthritis pathology, Arthritis physiopathology, Cytokines immunology, Mice, Transgenic, Tumor Necrosis Factor-alpha genetics
- Abstract
Arthritis spontaneously develops in mice expressing a human TNF-alpha transgene modified with the 3' untranslated region of beta-globin. We have backcrossed these mice onto the arthritis-susceptible DBA/1 background and found an acceleration of the onset of arthritis with successive generations of interbreeding. Bioactive TNF-alpha in primary synovial membrane cell cultures was significantly higher in the DBA/1 transgenic mice than in transgenic mice on the original background. Elevated levels of human TNF-alpha were accompanied by increases in synovial cell expression of murine IL-1beta and IL-6, but murine granulocyte-macrophage CSF, IFN-gamma, and IL-4 could not be detected. Interestingly, the anti-inflammatory cytokine IL-10 could be detected, but levels were not modulated by expression of the transgene. Analysis of the synovial membrane cell composition revealed that >50% of synovial cells were CD45-negative cells, presumably fibroblasts and endothelial cells, and the majority of CD45-expressing cells were neutrophils. Peritoneal macrophages and lymphocytes from the spleen, bone marrow, and lymph nodes required LPS stimulation to produce human TNF-alpha, indicating that, when activated, cells of these lineages were capable of expressing the transgene; however, few were found in synovial tissues. In contrast, fibroblasts derived from synovial tissue spontaneously released human TNF-alpha, and using immunohistochemical techniques, this cytokine was localized to fibroblast-like cells and chondrocytes. We propose that arthritis in DBA/1 human TNF-alpha transgenic mice is driven in part through the spontaneous expression of transgene by connective tissue cells, and there is little evidence of the participation of lymphocytes in this model.
- Published
- 1997
37. Dynamics of proinflammatory cytokine expression in the joints of mice with collagen-induced arthritis (CIA).
- Author
-
Marinova-Mutafchieva L, Williams RO, Mason LJ, Mauri C, Feldmann M, and Maini RN
- Subjects
- Animals, Ankle Joint, Hindlimb, Interferon-gamma biosynthesis, Interleukin-1 biosynthesis, Interleukin-6 biosynthesis, Lymph Nodes metabolism, Male, Mice, Mice, Inbred DBA, Synovial Membrane metabolism, Time Factors, Tumor Necrosis Factor-alpha biosynthesis, Arthritis, Experimental metabolism, Collagen, Inflammation Mediators metabolism
- Abstract
This report contains a description of the cellular localization and kinetics of proinflammatory cytokine expression in murine CIA, a model for rheumatoid arthritis. Tissue cryostat sections of undecalcified paws from type II collagen-immunized DBA/1 mice, taken 1-10 days after the onset of clinical arthritis, were examined for the presence of tumour necrosis factor-alpha (TNF-alpha), IL-1beta and IL-6 using an indirect immunoperoxidase technique. In parallel, interferon-gamma (IFN-gamma) production by lymph node cells, stimulated in vitro with type II collagen, was assessed as a marker of T cell activity. The main areas of TNF-alpha, IL-1beta and IL-6 expression were in the synovial lining layer and in tissue contiguous with cartilage and bone (the marginal zone), in particular at sites of pannus formation and joint erosion. There was a progressive increase in the number of TNF-alpha-, IL-1beta- and IL-6-positive cells from day 1 to day 10 of arthritis, during which time IFN-gamma production by CD4+ T cells from draining lymph nodes declined sharply. A further finding of potential significance was that TNF-alpha was consistently detected at day 1 of arthritis, whereas IL- 1beta-positive cells were not found until day 3, suggesting that the expression of TNF-alpha precedes that of IL-1beta.
- Published
- 1997
- Full Text
- View/download PDF
38. Readiness: observations and comments from a medical team deployment.
- Author
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Popper SE, Noble DE, Mason LJ, Schaffer LA, Glover JG, and Barkley MS
- Subjects
- Bosnia and Herzegovina, Program Development, Program Evaluation, United States, Warfare, Health Planning, Military Medicine
- Abstract
The evolving strategy of the United States in dealing with the changing world order calls for a force structure capable of fighting and winning two nearly simultaneous major regional conflicts and conducting a range of other military operations. Readiness is a key factor in this new strategy. Consequently, major paradigm shifts are occurring within the Air Force Medical Service. Maintaining current and accurate medical records on personnel to meet deployment requirements is a significant challenge. Historically, time and resources are consumed determining the deployability of troops prior to a deployment. This adds to the cost of doing business and increases the time required to clear the deploying team, even though there is an established process to avoid these very problems. The experience of a recent medical team deployment to Bosnia is discussed. Future directions given the implementation of TRI-CARE, the Preventive Health Assessment Program, and the Strategic Health Resourcing Plan are also considered.
- Published
- 1997
39. Surgical intervention and anesthetic management of the patient with Parkinson's disease.
- Author
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Mason LJ, Cojocaru TT, and Cole DJ
- Subjects
- Globus Pallidus surgery, Humans, Parkinson Disease diagnosis, Parkinson Disease drug therapy, Parkinson Disease physiopathology, Preoperative Care, Stereotaxic Techniques, Thalamus surgery, Anesthesia, Parkinson Disease surgery
- Abstract
With estimates as high as 1 million patients in the United States, Parkinson's disease is a relatively common neurological disorder. It has long been thought that the primary biochemical disturbance in Parkinson's disease is dopamine related. Accordingly, many drugs have been developed that increase the supply of dopamine, affect the biochemical balance of dopamine, or act as a dopamine substitute. These drugs may have significant interactions with anesthetic agents. In addition, there are several disease and drug-induced physiological aberrancies that can have profound anesthetic implications in the patient with Parkinson's disease (e.g., aspiration pneumonitis, myocardial irritability, hypotension, hypertension, and respiratory impairment). Although surgical therapy for Parkinson's disease has a long history, with the advent of advanced neuroimaging techniques there has been a resurgence of these procedures (e.g., pallidotomy and thalamotomy) for advanced stages of Parkinson's disease. It is likely that these surgical procedures will become more commonplace, possibly prolonging the lifespan of patients with Parkinson's disease. Even though these cases are typically performed with local anesthesia, there are several important caveats to consider in the management of these patients (e.g., airway access with CNS changes, hypertension, and tremor). It's incumbent on anesthesiologists to become familiar with the special needs of patients with Parkinson's disease and alter the "days in hell" attitude among these patients toward surgery and anesthesia.
- Published
- 1996
- Full Text
- View/download PDF
40. Synergy between anti-CD4 and anti-tumor necrosis factor in the amelioration of established collagen-induced arthritis.
- Author
-
Williams RO, Mason LJ, Feldmann M, and Maini RN
- Subjects
- Animals, Arthritis, Rheumatoid chemically induced, CD4-Positive T-Lymphocytes cytology, Collagen immunology, Collagen pharmacology, Drug Synergism, Extremities pathology, Immunoglobulin G blood, Immunoglobulin M blood, Joints pathology, Male, Mice, Mice, Inbred DBA, Time Factors, Antibodies, Monoclonal therapeutic use, Arthritis, Rheumatoid therapy, CD4 Antigens immunology, Tumor Necrosis Factor-alpha immunology
- Abstract
Anti-CD4 treatment is reported to prevent collagen-induced arthritis if administered before the onset of clinical disease but has relatively little effect on established arthritis. In contrast, we have recently shown that anti-tumor necrosis factor alpha/beta (TNF) treatment reduces the severity of established arthritis. We now study the effect of combined administration of anti-CD4 monoclonal antibody (YTS 191.1.2/YTA 3.1.2) and anti-TNF monoclonal antibody (TN3-19.12) in established arthritis. Anti-CD4 treatment caused some reduction in paw-swelling but did not significantly prevent joint erosion. A suboptimal dose of anti-TNF alone had no significant effect on arthritis. In contrast, anti-CD4 plus suboptimal anti-TNF significantly reduced paw-swelling, limb involvement, and joint erosion. As previously reported, an optimal dose of anti-TNF alone inhibited paw-swelling, limb involvement, and joint erosion. However, optimal anti-TNF combined with anti-CD4 caused significantly greater reductions in paw-swelling and joint erosion than those achieved by optimal anti-TNF alone. Coadministration of anti-CD4 was also effective in preventing an antibody response to the hamster anti-TNF antibody, which may have implications for long-term therapy in human disease. Thus anti-CD4 acts synergistically with anti-TNF in ameliorating established collagen-induced arthritis and this combined therapeutic approach may provide effective long-term control of rheumatoid arthritis.
- Published
- 1994
- Full Text
- View/download PDF
41. Quasilocal mass constructions with positive energy.
- Author
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Dougan AJ and Mason LJ
- Published
- 1991
- Full Text
- View/download PDF
42. Effects of scale insect herbivory and shading on net gas exchange and growth of a subtropical tree species (Guaiacum sanctum L.).
- Author
-
Schaffer B and Mason LJ
- Abstract
The scale insect, Toumeyella sp., feeds exclusively on the subtropical hammock tree lignum vitae (Guaiacum sanctum L.). The combined effects of scale herbivory and shading on leaf gas exchange characteristics and growth of lignum vitae trees were studied using a factorial design. Trees grown in full sun or in 75% shade were manually infested with scale or left noninfested. Beginning 4 weeks after infestation, net CO
2 assimilation, stomatal conductance, transpiration, internal partial pressure of CO2 , and water-use efficiency were determined on single-leaves at 4-week intervals for trees in each treatment. At the end of the experiment, net CO2 assimilation was determined for whole plants. Total leaf area, leaf, stem, and root dry weights, and leaf chlorophyll and nitrogen concentrations were also determined. Scale infested trees generally had lower net CO2 assimilation, stomatal conductance, and transpiration rates as well as less leaf area, and root, stem, and leaf dry weights than noninfested trees. Twenty four weeks after the shade treatment was imposed, sun-grown trees had approximately twice the leaf area of shade-grown trees. Shade-grown trees compensated for the reduced leaf area by increasing their photosynthetic efficiency. This resulted in no difference in light saturated net CO2 assimilation on a whole plant basis between sun-grown and shade-grown trees. Chlorophyll and nitrogen concentrations per unit leaf area were greater in leaves of shade-grown trees than in leaves of sun-grown trees. Shading and herbivory by Toumeyella sp. each resulted in decreased growth of Guaiacum sanctum. Scale insect herbivory did not result in greater detrimental effects on leaf gas exchange characteristics for shade-grown than for sun-grown trees. Herbivory by Toumeyella resulted in a greater decrease in tree growth for sun-grown than for shade-grown trees.- Published
- 1990
- Full Text
- View/download PDF
43. Sampling range of male sweetpotato weevils (Cylas formicarius elegantulus) (Summers) (Coleoptera: Curculionidae) to pheromone traps: Influence of pheromone dosage and lure age.
- Author
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Mason LJ, Jansson RK, and Heath RR
- Abstract
Studies were conducted to determine the effects of sex pheromone dosage and lure age on movement of male sweetpotato weevils (SPW),Cylas formicarius elegantulus (Summers), using mark-release-recapture techniques. SPW trap counts from various downwind distances were compared for dosages ranging from 0.01 to 10.0 μg and lure ages ranging from fresh (0 days old) to 64 days old. The percentages of male SPW recaptured decreased with an increase in release distance and decreased with a decrease in dosage at each corresponding distance. Most SPW were caught within the first 16-hr period. Slopes of percent recapture vs. release distance for the two higher dosages (10 μg and 1.0 μg) differed from those of the two lower dosages (0.1 and 0.01 μg) but did not differ from each other. Intercepts were similar among the three higher dosages. Slopes did not differ among the five lure ages examined. Intercepts differed between fresh (0 days old) and 24-day-old septa at 16 hr and between fresh (0 days old) and 34-day-old septa at 40 hr. Previous exposure to pheromone (conditioning) did not increase percentages of SPW recaptured. Results indicate that male SPW are capable of traversing distances of at least 280 m in 16 hr. The pheromone tested in this study appears to be effective at dosages lower than any other coleopteran sex-pheromone system. Incorporation of this pheromone into a SPW management system may effectively reduce the use of insecticides.
- Published
- 1990
- Full Text
- View/download PDF
44. Paradoxical air embolism associated with a central total parenteral nutrition catheter.
- Author
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Jacobsen WK, Briggs BA, and Mason LJ
- Subjects
- Adult, Embolism, Air therapy, Equipment Failure, Humans, Male, Parenteral Nutrition, Total, Catheterization adverse effects, Embolism, Air etiology
- Abstract
Central vein cannulation is used frequently as a route for total parenteral nutrition (TPN); however, it is not without complications. This report describes a paradoxical air embolism resulting in circulatory collapse and in residual neurological deficit.
- Published
- 1983
- Full Text
- View/download PDF
45. Temperature instability as an early predictive factor of brain death in paediatric near-drowning victims.
- Author
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Mason LJ, Jacobsen WK, Lau CA, Roddy SM, Briggs BA, and Hough JM
- Subjects
- Brain Damage, Chronic etiology, Brain Damage, Chronic physiopathology, Brain Damage, Chronic therapy, Child, Child, Preschool, Critical Care, Fresh Water, Humans, Infant, Near Drowning complications, Near Drowning physiopathology, Resuscitation, Body Temperature Regulation, Brain Death, Near Drowning therapy
- Abstract
Predicting outcome after near-drowning has been extensively studied. During four years, 42 near drowned children were aggressively treated with positive pressure ventilation, barbiturates and hypothermia. This mode of treatment makes it difficult to clinically assess the child's prognosis. Temperature instability after rewarming is an early negative predictive factor following treatment of near-drowning, and in conjunction with cerebral flow studies avoids the potential commitment to prolonged and unwarranted cardiovascular and respiratory support.
- Published
- 1985
46. Leg lift and maximum inspiratory force, clinical signs of neuromuscular blockade reversal in neonates and infants.
- Author
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Mason LJ and Betts EK
- Subjects
- Humans, Infant, Infant, Newborn, Intermittent Positive-Pressure Ventilation, Muscle Contraction, Neuromuscular Junction innervation, Reflex drug effects, Leg physiology, Neuromuscular Blocking Agents pharmacology, Neuromuscular Junction drug effects, Respiration
- Published
- 1980
- Full Text
- View/download PDF
47. Correlation of spontaneous respiration and neurologic damage in near-drowning.
- Author
-
Jacobsen WK, Mason LJ, Briggs BA, Schneider S, and Thompson JC
- Subjects
- Apnea etiology, Child, Preschool, Coma etiology, Humans, Infant, Prognosis, Time Factors, Brain Diseases etiology, Drowning complications, Drowning mortality, Respiration
- Abstract
Twenty-six near-drowning children were assessed for neurologic damage with the Glasgow Coma Score, and for spontaneous respirations after CPR. All children had a Glasgow Coma Score of 3 or 4; after resuscitation, 13 children had spontaneous respiration and 13 were apneic. The 13 children with spontaneous respiration suffered little or no residual neurologic impairment. Those children with apnea had severe neurologic impairment or died despite treatment. It appears that the present of spontaneous respirations correlated with surviving a near-drowning episode with minimal or no neurologic deficit and may be of benefit as a prognostic indicator.
- Published
- 1983
- Full Text
- View/download PDF
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