31 results on '"Lackey E"'
Search Results
2. Roles of mucus adhesion and cohesion in cough clearance
- Author
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Lackey, E., Rubinstein, M., Boucher, R.C., Dennis, R.G., Atieh, E., Shenkute, N.T., Shenoy, S., Button, B., Williams, R., Goodell, H.P., Cai, L.-H., and Chen, Y.-C.
- Subjects
fluids and secretions ,respiratory system ,respiratory tract diseases - Abstract
Clearance of intrapulmonary mucus by the high-velocity airflow generated by cough is the major rescue clearance mechanism in subjects with mucoobstructive diseases and failed cilial-dependent mucus clearance, e.g., subjects with cystic fibrosis (CF) or chronic obstructive pulmonary disease (COPD). Previous studies have investigated the mechanical forces generated at airway surfaces by cough but have not considered the effects of mucus biophysical properties on cough efficacy. Theoretically, mucus can be cleared by cough from the lung by an adhesive failure, i.e., breaking mucus-cell surface adhesive bonds and/or by cohesive failure, i.e., directly fracturing mucus. Utilizing peel-testing technologies, mucus-epithelial surface adhesive and mucus cohesive strengths were measured. Because both mucus concentration and pH have been reported to alter mucus biophysical properties in disease, the effects of mucus concentration and pH on adhesion and cohesion were compared. Both adhesive and cohesive strengths depended on mucus concentration, but neither on physiologically relevant changes in pH nor bicarbonate concentration. Mucus from bronchial epithelial cultures and patient sputum samples exhibited similar adhesive and cohesive properties. Notably, the magnitudes of both adhesive and cohesive strength exhibited similar velocity and concentration dependencies, suggesting that viscous dissipation of energy within mucus during cough determines the efficiency of cough clearance of diseased, hyperconcentrated, mucus. Calculations of airflow-induced shear forces on airway mucus related to mucus concentration predicted substantially reduced cough clearance in small versus large airways. Studies designed to improve cough clearance in subjects with mucoobstructive diseases identified reductions of mucus concentration and viscous dissipation as key therapeutic strategies.
- Published
- 2018
- Full Text
- View/download PDF
3. A scale for measuring the ability of children in geography
- Author
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Lackey, E. E.
- Published
- 1918
4. Multiple Injection Port Simulation for Resin Injection Pultrusion
- Author
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Rahatekar, S.S., primary, Roux, J.A., additional, Lackey, E., additional, and Vaughan, J.G., additional
- Published
- 2005
- Full Text
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5. Permeability Impact on the Pressure Rise in a Pultrusion Die
- Author
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Raper, K. S., primary, Roux, J. A., additional, Vaughan, J. G., additional, and Lackey, E., additional
- Published
- 1999
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6. The Selection of Geographical Material for Junior High School.
- Author
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Lackey, E. E.
- Published
- 1926
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7. The Classification and Use of Geographic Principles.
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Lackey, E. E.
- Published
- 1924
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8. The Geography of a Country.
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Lackey, E. E.
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- 1920
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9. Measuring the Ability of Children in Geography.
- Author
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Lackey, E. E.
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- 1918
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10. Worcester Meeting of the National Council of Geography Teachers.
- Author
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Lackey, E. E.
- Published
- 1930
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11. Special Railroad Rates: National Council Meeting
- Author
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Lackey, E. E., primary
- Published
- 1932
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12. The Habitat and Description of a New Genus of Sulphur Bacterium
- Author
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Lackey, J. B., primary and Lackey, E. W., additional
- Published
- 1961
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13. Late Diagnostic Clues in Rapidly Progressing Probable Heidenhain Variant of Creutzfeldt-Jakob Disease.
- Author
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Gaini R, Denniss J, and Lackey E
- Abstract
Presenting symptoms of sporadic Creutzfeldt-Jakob disease (sCJD) are variable, and as imaging and EEG may be normal in the early to middle stages of the disease process, serial testing is vital when there is clinical suspicion for sCJD. We present a case of probable Heidenhain variant of sCJD (HvCJD) with notable rapid progression. A 72-year-old woman presented with neurological decline following new-onset visual changes. Over the course of 3 weeks, she developed ataxia followed by paranoia, memory impairment, and visual hallucinations. An extensive workup from 1 week prior at an outside hospital was unrevealing and included two magnetic resonance imaging (MRI) studies read as normal and an EEG without periodic sharp wave complexes. Repeat of imaging at our hospital showed cortical restricted diffusion in the right occipital lobe. In combination with new periodic sharp wave complexes visualized on prolonged EEG, concern was raised for sCJD. Palliative care was consulted early in the hospitalization, and the patient was transitioned to comfort care and discharged 3 days after admission. She declined quickly and passed away at home within a week, one day before her send out CSF sample resulted with a positive real-time quaking-induced conversion (RT-QuiC) and markedly elevated T-tau protein and 14-3-3 gamma. As there is no treatment for this fatal disease, palliative engagement and discussion of goals of care in cases of CJD is critical in providing compassionate care for the patient and their family. High clinical suspicion warrants discussion of comfort care measures even prior to confirmation with RT-QuiC., Competing Interests: Rahul Gaini has nothing to disclose. Julia Denniss has nothing to disclose. Elijah Lackey has received compensation for advisory boards from EMD Serono, Sanofi, and Doximity., (Copyright © 2024 Rahul Gaini et al.)
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- 2024
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14. Reasons for Hospital Admission in Individuals With Multiple Sclerosis.
- Author
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Paredes D, Lackey E, and Shah S
- Abstract
Background: Health care utilization is higher in individuals with multiple sclerosis (MS) than in the general population. However, there are limited data on the reasons for their hospital admissions. Our primary objective is to analyze the reasons for the hospitalization of individuals with MS with the goal of identifying preventable causes., Methods: We conducted a retrospective analysis of a cohort of adults with a confirmed diagnosis of MS admitted to Duke University Hospital between January 2018 and January 2020. This yielded a cohort of 210 individuals. Data were analyzed using descriptive statistics., Results: The most common reason for admission was urinary tract infection (UTI; 10.3%). The average length of stay was 6.1 days for the individuals with MS vs 5.5 days for the general population. The 30-day readmission rates were 14.9% and 15.5%, respectively. A significant number of admitted patients were not on any disease-modifying therapy (DMT), and no difference in median age was identified between those with a DMT vs those without., Conclusions: Length of stay and readmission rates were similar to those of the general population in this contemporary cohort. Given the prevalence of bladder dysfunction in MS, it is not surprising that a UTI was the most common reason for admission. Actively addressing management of and techniques for bladder dysfunction may decrease the admission rate for individuals with MS. Though we now have more treatment options for MS, many individuals with the highest health care utilization are not on a DMT. Future research is needed to identify the factors that can be addressed to support these patients and reduce preventable hospitalizations., (© 2024 Consortium of Multiple Sclerosis Centers.)
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- 2024
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15. Beyond biopsy for neurosarcoidosis: A review of blood and CSF biomarkers.
- Author
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Lackey E, Shen J, Sharma A, and Eckstein C
- Subjects
- Humans, Biopsy, Peptidyl-Dipeptidase A cerebrospinal fluid, Peptidyl-Dipeptidase A blood, Receptors, Interleukin-2 blood, Sarcoidosis cerebrospinal fluid, Sarcoidosis diagnosis, Sarcoidosis blood, Biomarkers cerebrospinal fluid, Biomarkers blood, Central Nervous System Diseases cerebrospinal fluid, Central Nervous System Diseases diagnosis, Central Nervous System Diseases blood
- Abstract
Neurosarcoidosis, a rare granulomatous disease, causes inflammation and damage to the central nervous system (CNS). A major diagnostic challenge in neurosarcoidosis is the absence of well-defined biomarkers. The need for biopsy to make the diagnosis can lead to delays and misdiagnosis if histopathology is inaccessible or indeterminate, highlighting the need for more accessible diagnostic indicators. The current gold standard for a "definite" neurosarcoidosis diagnosis requires biopsy of CNS tissue revealing non-caseating granulomas. However, such biopsies are inherently invasive and carry associated procedural risks. Notably, angiotensin-converting enzyme (ACE), commonly associated with systemic sarcoidosis, is recognized as a poor biomarker for neurosarcoidosis due to its lack of accuracy in the context of CNS involvement. Furthermore, imaging in neurosarcoidosis, while widely utilized and important for narrowing the diagnosis, lacks specificity. Decades of research have yielded molecular and immunologic biomarkers-soluble interleukin-2 receptor (IL-2R), serum amyloid A1, the CD4/CD8 ratio, neopterin, interferon-gamma (IFN-γ), and chemokine ligand 2 (CCL2)-that hold potential for improving diagnostic accuracy. However, these biomarkers are not yet established in clinical care as they may be difficult to obtain and are derived from small studies. They also suffer from a lack of specificity against other inflammatory and infectious central nervous system diseases. New biomarkers are needed for use alongside those previously discovered to improve diagnosis of this rare disease. This review synthesizes existing literature on neurosarcoidosis biomarkers, aiming to establish a foundation for further research in this evolving field. It also consolidates information on biomarkers of systemic sarcoidosis such as IL-8 and soluble CD40L that have not yet been studied in neurosarcoidosis but hold potential as markers of CNS disease., Competing Interests: Declaration of competing interest None., (Copyright © 2023. Published by Elsevier B.V.)
- Published
- 2024
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16. Adalimumab as treatment for neurosarcoidosis: A case series.
- Author
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Shen J, Sugita M, Linares-Lopez A, Shah S, Eckstein C, and Lackey E
- Subjects
- Humans, Female, Male, Middle Aged, Adult, Anti-Inflammatory Agents therapeutic use, Treatment Outcome, Aged, Sarcoidosis drug therapy, Sarcoidosis diagnostic imaging, Adalimumab therapeutic use, Central Nervous System Diseases drug therapy, Central Nervous System Diseases diagnostic imaging
- Abstract
Sarcoidosis is a disease characterized by non-caseating granulomas that can involve the central nervous system as neurosarcoidosis. This challenging disease is currently managed with high dose steroids, and sometimes the addition of infliximab. Other TNA-alpha inhibitors have not been studied as rigorously. We discovered ten neurosarcoidosis patients who were on an alternative TNA-alpha inhibitor, adalimumab. Eight patients had a positive response clinically and radiographically to adalimumab., Competing Interests: Declaration of competing interest The authors declare no relevant disclosures or competing interests., (Copyright © 2023. Published by Elsevier B.V.)
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- 2024
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17. Neurosarcoidosis causing hydrocephalus: A case series.
- Author
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Lackey E, Shen J, Veal K, Shah S, and Eckstein C
- Subjects
- Humans, Seizures, Central Nervous System Diseases complications, Central Nervous System Diseases diagnostic imaging, Hydrocephalus etiology, Hydrocephalus complications, Sarcoidosis complications, Sarcoidosis diagnostic imaging
- Abstract
Sarcoidosis is a granulomatous inflammatory disease that rarely affects the central nervous system as neurosarcoidosis. Neurosarcoidosis can affect any part of the nervous system causing a wide variety of clinical presentations ranging from seizures to optic neuritis. Here, we highlight rare cases of obstructive hydrocephalus in patients with neurosarcoidosis to make clinicians aware of this potential disease complication., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023 Elsevier B.V. All rights reserved.)
- Published
- 2023
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18. Neurosarcoidosis: Diagnostic Challenges and Mimics A Review.
- Author
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Shen J, Lackey E, and Shah S
- Subjects
- Humans, Biopsy, Granuloma diagnosis, Central Nervous System Diseases diagnosis, Central Nervous System Diseases pathology, Sarcoidosis diagnosis, Sarcoidosis pathology
- Abstract
Purpose of Review: Neurosarcoidosis is a rare manifestation of sarcoidosis that is challenging to diagnose. Biopsy confirmation of granulomas is not sufficient, as other granulomatous diseases can present similarly. This review is intended to guide the clinician in identifying key conditions to exclude prior to concluding a diagnosis of neurosarcoidosis., Recent Findings: Although new biomarkers are being studied, there are no reliable tests for neurosarcoidosis. Advances in serum testing and imaging have improved the diagnosis for key mimics of neurosarcoidosis in certain clinical scenarios, but biopsy remains an important method of differentiation. Key mimics of neurosarcoidosis in all cases include infections (tuberculosis, fungal), autoimmune disease (vasculitis, IgG4-related disease), and lymphoma. As neurosarcoidosis can affect any part of the nervous system, patients should have a unique differential diagnosis tailored to their clinical presentation. Although biopsy can assist with excluding mimics, diagnosis is ultimately clinical., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)
- Published
- 2023
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19. Steroid-induced weight gain in the treatment of neurosarcoidosis.
- Author
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Lackey E, Shen J, Veal K, Paredes D, Masha N, Shah S, and Eckstein C
- Subjects
- Humans, Steroids, Central Nervous System Diseases drug therapy, Sarcoidosis drug therapy
- Abstract
Competing Interests: Declaration of Competing Interest The authors declare no conflicts of interest relevant to this manuscript. Christopher Eckstein has received research funding from Sanofi, Genzyme, EMD Serono. He has received Honoraria from Viela Bio. Suma Shah has received research support from Verasci and Biogen. She has received honoraria from EMD Serono and Novartis.
- Published
- 2023
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20. Leber's Hereditary Optic Neuropathy Plus Causing Recurrent Myelopathy due to an MT-DN1 Mutation at G3635A.
- Author
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Lackey E, Lefland A, and Eckstein C
- Abstract
A 51-year-old man with known Leber's hereditary optic neuropathy (LHON) presented with worsening lower extremity weakness and numbness. Following an episode of myelopathy two years before, he had been ambulating with a walker but over two weeks became wheelchair bound. He also developed a sensory level below the T4 dermatome to light touch, pinprick, and vibration. MRI of his cervical and thoracic spine showed a nonenhancing T2 hyperintense lesion extending from C2 to T12. At his presentation two years earlier, he was found to have a longitudinally extensive myelopathy attributed to his LHON. Genetic testing revealed a 3635 guanine to adenine mutation. MRI at that presentation demonstrated a C1-T10 lesion involving the central and posterior cord but, unlike the new lesion, did not involve the ventral and lateral horns. Given the similarity to his prior presentation and a negative evaluation for alternative etiologies, he was thought to have recurrent myelopathy secondary to Leber's Plus. To our knowledge, recurrent myelopathy due specifically to the G3635A mutation in Leber's Plus has not been reported previously., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2022 Elijah Lackey et al.)
- Published
- 2022
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21. Efficacy of a Virtual Education Program for Family Caregivers of Persons Living with Dementia.
- Author
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Noel MA, Lackey E, Labi V, and Bouldin ED
- Subjects
- Activities of Daily Living, Humans, Self Efficacy, Surveys and Questionnaires, Caregivers education, Dementia
- Abstract
Background: Family caregivers of people with dementia often experience negative impacts including stress and burden. Psychoeducational programs can reduce these negative outcomes., Objective: To evaluate whether this virtual caregiver education program changes caregiver confidence, self-efficacy, and burden relative to controls., Methods: This was a pre-post comparison of a five-week, synchronous, virtual caregiver education program delivered by a clinician and caregiver support specialist covering aspects of dementia, including changes in cognition, behavior, functional abilities, caregiver-care recipient roles, communication, and caregiver self-care. Caregivers (n = 90) were surveyed at baseline, at completion of intervention, and three months thereafter; controls (n = 44) were surveyed at two points six weeks apart. We compared validated measures of caregiver confidence, self-efficacy, and burden using generalized estimating equations., Results: Participants' confidence and self-efficacy increased over follow-up compared with controls (p < 0.01 for intervention*time in regression models). There was no difference in burden. All participants (100%) reported perceived increased knowledge, 97% perceived increased confidence, and 95% perceived increased ability to manage dementia-related behaviors after the course., Conclusion: This virtual caregiver education program was effective in improving caregiver confidence and self-efficacy and participants' self-reported impact was equivalent to those who had taken previous courses in person. Caregivers with greater confidence and self-efficacy have been shown to have better health outcomes and decreased stress and depressive symptoms. Health professionals, health care organizations, and public health agencies should consider using efficacious virtual caregiver education programs in rural and other community settings, during public health crises, or in standard practice as an alternative to in-person programs.
- Published
- 2022
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22. Negative Diffusion Weighted Imaging on Magnetic Resonance Imaging of the Brain in Creutzfeldt-Jakob Disease.
- Author
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Lackey E, Shah-Zamora DP, Hawes J, and Liu AJ
- Abstract
A 76-year-old Caucasian woman initially presented to the Duke Memory Disorders clinic with a 9-month history of a rapid decline in cognitive, motor, and neuropsychiatric function. On initial presentation, the patient required assistance with activities of daily living. On neurological examination, she was found to have Gerstmann's syndrome along with appendicular apraxia. A positional tremor was noted without myoclonus or fasciculations. She had a paucity of speech and was unable to write her own name. Snout and grasp reflexes were present. Episodes of inappropriate laughter were noted during the exam. She was admitted to the inpatient neurology service for further evaluation. The Diffusion Weighted Imaging sequence on Magnetic Resonance Imaging of the brain was negative for restricted diffusion. An electroencephalogram was unremarkable. Cerebrospinal fluid analysis for Real-Time Quaking-Induced Conversion assay was positive along with an elevated 14-3-3 and increased total Tau protein levels. There was no family history of Creutzfeldt-Jakob disease. The cerebral spinal fluid results were consistent with a diagnosis of Creutzfeldt-Jakob disease, despite the negative MRI brain findings., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2020 Elijah Lackey et al.)
- Published
- 2020
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23. Adhesive and Cohesive Peel Force Measurement of Human Airway Mucus.
- Author
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Goodell HP, Shenoy SK, Shenkute NT, Lackey E, Dennis RG, and Button B
- Abstract
In health, the high-speed airflow associated with cough represents a vital backup mechanism for clearing accumulated mucus from our airways. However, alterations in the mucus layer in cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD) leads to the mucus layer adhered to the airway surfaces, representing the nidus of chronic lung infection. To understand what is different about diseased mucus and why cough clearance is defective, there is a need for techniques to quantify the strength of the interactions limiting the ability of airflow to strip mucus from the airway surface ( i.e ., adhesive strength) or tear mucus apart ( i.e ., cohesive strength). To overcome the issues with measuring these properties in a soft ( i.e ., low elastic modulus) mucus layer, we present here novel peel-testing technologies capable of quantifying the mucus adhesive strength on cultured airway cells and cohesive strength of excised mucus samples. While this protocol focuses on measurements of airway mucus, this approach can easily be adapted to measuring adhesive/cohesive properties of other soft biological materials., Competing Interests: Competing interests None for any authors listed.
- Published
- 2019
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24. Roles of mucus adhesion and cohesion in cough clearance.
- Author
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Button B, Goodell HP, Atieh E, Chen YC, Williams R, Shenoy S, Lackey E, Shenkute NT, Cai LH, Dennis RG, Boucher RC, and Rubinstein M
- Subjects
- Bicarbonates, Cell Adhesion, Cystic Fibrosis, Epithelial Cells, Humans, Hydrogen-Ion Concentration, Lung Diseases, Mucociliary Clearance physiology, Mucus chemistry, Respiratory Physiological Phenomena, Rheology, Sputum, Cough pathology, Mucus physiology
- Abstract
Clearance of intrapulmonary mucus by the high-velocity airflow generated by cough is the major rescue clearance mechanism in subjects with mucoobstructive diseases and failed cilial-dependent mucus clearance, e.g., subjects with cystic fibrosis (CF) or chronic obstructive pulmonary disease (COPD). Previous studies have investigated the mechanical forces generated at airway surfaces by cough but have not considered the effects of mucus biophysical properties on cough efficacy. Theoretically, mucus can be cleared by cough from the lung by an adhesive failure, i.e., breaking mucus-cell surface adhesive bonds and/or by cohesive failure, i.e., directly fracturing mucus. Utilizing peel-testing technologies, mucus-epithelial surface adhesive and mucus cohesive strengths were measured. Because both mucus concentration and pH have been reported to alter mucus biophysical properties in disease, the effects of mucus concentration and pH on adhesion and cohesion were compared. Both adhesive and cohesive strengths depended on mucus concentration, but neither on physiologically relevant changes in pH nor bicarbonate concentration. Mucus from bronchial epithelial cultures and patient sputum samples exhibited similar adhesive and cohesive properties. Notably, the magnitudes of both adhesive and cohesive strength exhibited similar velocity and concentration dependencies, suggesting that viscous dissipation of energy within mucus during cough determines the efficiency of cough clearance of diseased, hyperconcentrated, mucus. Calculations of airflow-induced shear forces on airway mucus related to mucus concentration predicted substantially reduced cough clearance in small versus large airways. Studies designed to improve cough clearance in subjects with mucoobstructive diseases identified reductions of mucus concentration and viscous dissipation as key therapeutic strategies., Competing Interests: The authors declare no conflict of interest.
- Published
- 2018
- Full Text
- View/download PDF
25. The Globalization of Cooperative Groups.
- Author
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Valdivieso M, Corn BW, Dancey JE, Wickerham DL, Horvath LE, Perez EA, Urton A, Cronin WM, Field E, Lackey E, and Blanke CD
- Subjects
- Africa, Asia, Canada, Humans, Latin America, National Cancer Institute (U.S.), United States, Biomedical Research organization & administration, Clinical Trials as Topic, Cooperative Behavior, Internationality, Neoplasms
- Abstract
The National Cancer Institute (NCI)-supported adult cooperative oncology research groups (now officially Network groups) have a longstanding history of participating in international collaborations throughout the world. Most frequently, the US-based cooperative groups work reciprocally with the Canadian national adult cancer clinical trial group, NCIC CTG (previously the National Cancer Institute of Canada Clinical Trials Group). Thus, Canada is the largest contributor to cooperative groups based in the United States, and vice versa. Although international collaborations have many benefits, they are most frequently utilized to enhance patient accrual to large phase III trials originating in the United States or Canada. Within the cooperative group setting, adequate attention has not been given to the study of cancers that are unique to countries outside the United States and Canada, such as those frequently associated with infections in Latin America, Asia, and Africa. Global collaborations are limited by a number of barriers, some of which are unique to the countries involved, while others are related to financial support and to US policies that restrict drug distribution outside the United States. This article serves to detail the cooperative group experience in international research and describe how international collaboration in cancer clinical trials is a promising and important area that requires greater consideration in the future., (Copyright © 2015 Elsevier Inc. All rights reserved.)
- Published
- 2015
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26. Comparative evolution of morphological regulatory functions in Candida species.
- Author
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Lackey E, Vipulanandan G, Childers DS, and Kadosh D
- Subjects
- Candida cytology, Candida metabolism, Candida physiology, Fungal Proteins genetics, Mycelium cytology, Mycelium metabolism, Candida genetics, Evolution, Molecular, Fungal Proteins metabolism, Mycelium genetics
- Abstract
Morphological transitions play an important role in virulence and virulence-related processes in a wide variety of pathogenic fungi, including the most commonly isolated human fungal pathogen Candida albicans. While environmental signals, transcriptional regulators, and target genes associated with C. albicans morphogenesis are well-characterized, considerably little is known about morphological regulatory mechanisms and the extent to which they are evolutionarily conserved in less pathogenic and less filamentous non-albicans Candida species (NACS). We have identified specific optimal filament-inducing conditions for three NACS (C. tropicalis, C. parapsilosis, and C. guilliermondii), which are very limited, suggesting that these species may be adapted for niche-specific filamentation in the host. Only a subset of evolutionarily conserved C. albicans filament-specific target genes were induced upon filamentation in C. tropicalis, C. parapsilosis, and C. guilliermondii. One of the genes showing conserved expression was UME6, a key filament-specific regulator of C. albicans hyphal development. Constitutive high-level expression of UME6 was sufficient to drive increased filamentation as well as biofilm formation and partly restore conserved filament-specific gene expression in both C. tropicalis and C. parapsilosis, suggesting that evolutionary differences in filamentation ability among pathogenic Candida species may be partially attributed to alterations in the expression level of a conserved filamentous growth machinery. In contrast to UME6, NRG1, an important repressor of C. albicans filamentation, showed only a partly conserved role in controlling NACS filamentation. Overall, our results suggest that C. albicans morphological regulatory functions are partially conserved in NACS and have evolved to respond to more specific sets of host environmental cues.
- Published
- 2013
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27. RNAi-mediated down-regulation of DCL1 and AGO1 induces developmental changes in resynthesized Arabidopsis allotetraploids.
- Author
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Lackey E, Ng DW, and Chen ZJ
- Subjects
- Arabidopsis Proteins metabolism, Argonaute Proteins, Cell Cycle Proteins metabolism, Gene Expression Regulation, Developmental, Gene Expression Regulation, Plant, MicroRNAs metabolism, Phenotype, Plants, Genetically Modified, RNA, Small Interfering metabolism, Ribonuclease III metabolism, Arabidopsis genetics, Arabidopsis growth & development, Arabidopsis Proteins genetics, Cell Cycle Proteins genetics, Down-Regulation genetics, Polyploidy, RNA Interference, Ribonuclease III genetics
- Abstract
Both natural and newly synthesized allopolyploids display nonadditive gene expression changes through genetic and epigenetic mechanisms. The nonadditively expressed genes include many microRNA (miRNA) targets, suggesting a role for miRNAs and their targets in morphological variation in the allopolyploids and their progenitors. We produced dominant-negative transgenic allotetraploid plants in Arabidopsis using RNA interference (RNAi) that downregulates the expression of miRNA biogenesis genes, including DCL1 and AGO1. RNAi of DCL1 and AGO1 led to dominant negative phenotypes and decreased accumulation of several miRNAs and a tasiRNA tested in the transgenic resynthesized allotetraploids. The results demonstrated that miRNA biogenesis genes are effectively downregulated in the resynthesized allotetraploids containing redundant homoeologous genes that are difficult to be manipulated by conventional mutation screens. These lines will be useful for studying the effects of miRNA biogenesis genes on growth and developmental variation in the allopolyploids.
- Published
- 2010
- Full Text
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28. Altered circadian rhythms regulate growth vigour in hybrids and allopolyploids.
- Author
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Ni Z, Kim ED, Ha M, Lackey E, Liu J, Zhang Y, Sun Q, and Chen ZJ
- Subjects
- Arabidopsis classification, Arabidopsis Proteins genetics, Arabidopsis Proteins metabolism, Base Sequence, Biological Clocks genetics, Biological Clocks physiology, Chlorophyll metabolism, Chromatin genetics, Circadian Rhythm genetics, DNA-Binding Proteins genetics, DNA-Binding Proteins metabolism, Epigenesis, Genetic, Gene Expression Regulation, Plant genetics, Plants, Genetically Modified, Starch biosynthesis, Transcription Factors genetics, Transcription Factors metabolism, Arabidopsis genetics, Arabidopsis growth & development, Circadian Rhythm physiology, Hybridization, Genetic, Polyploidy
- Abstract
Segregating hybrids and stable allopolyploids display morphological vigour, and Arabidopsis allotetraploids are larger than the parents Arabidopsis thaliana and Arabidopsis arenosa-the mechanisms for this are unknown. Circadian clocks mediate metabolic pathways and increase fitness in animals and plants. Here we report that epigenetic modifications of the circadian clock genes CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY) and their reciprocal regulators TIMING OF CAB EXPRESSION 1 (TOC1) and GIGANTEA (GI) mediate expression changes in downstream genes and pathways. During the day, epigenetic repression of CCA1 and LHY induced the expression of TOC1, GI and downstream genes containing evening elements in chlorophyll and starch metabolic pathways in allotetraploids and F(1) hybrids, which produced more chlorophyll and starch than the parents in the same environment. Mutations in cca1 and cca1 lhy and the daily repression of cca1 by RNA interference (RNAi) in TOC1::cca1(RNAi) transgenic plants increased the expression of downstream genes and increased chlorophyll and starch content, whereas constitutively expressing CCA1 or ectopically expressing TOC1::CCA1 had the opposite effect. The causal effects of CCA1 on output traits suggest that hybrids and allopolyploids gain advantages from the control of circadian-mediated physiological and metabolic pathways, leading to growth vigour and increased biomass.
- Published
- 2009
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29. RNAi of met1 reduces DNA methylation and induces genome-specific changes in gene expression and centromeric small RNA accumulation in Arabidopsis allopolyploids.
- Author
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Chen M, Ha M, Lackey E, Wang J, and Chen ZJ
- Subjects
- Centromere metabolism, Chromosomes, Plant genetics, DNA Transposable Elements genetics, Genes, Plant, Genome, Plant genetics, Heterochromatin genetics, Promoter Regions, Genetic genetics, RNA, Plant genetics, RNA, Small Interfering genetics, RNA, Small Interfering metabolism, Up-Regulation genetics, Arabidopsis genetics, Arabidopsis Proteins genetics, DNA (Cytosine-5-)-Methyltransferases genetics, DNA Methylation, Gene Expression Regulation, Plant, Polyploidy, RNA Interference, RNA, Plant metabolism
- Abstract
Changes in genome structure and gene expression have been documented in both resynthesized and natural allopolyploids that contain two or more divergent genomes. The underlying mechanisms for rapid and stochastic changes in gene expression are unknown. Arabidopsis suecica is a natural allotetraploid derived from the extant A. thaliana and A. arenosa genomes that are homeologous in the allotetraploid. Here we report that RNAi of met1 reduced DNA methylation and altered the expression of approximately 200 genes, many of which encode transposons, predicted proteins, and centromeric and heterochromatic RNAs. Reduced DNA methylation occurred frequently in promoter regions of the upregulated genes, and an En/Spm-like transposon was reactivated in met1-RNAi A. suecica lines. Derepression of transposons, heterochromatic repeats, and centromeric small RNAs was primarily derived from the A. thaliana genome, and A. arenosa homeologous loci were less affected by methylation defects. A high level of A. thaliana centromeric small RNA accumulation was correlated with hypermethylation of A. thaliana centromeres. The greater effects of reduced DNA methylation on transposons and centromeric repeats in A. thaliana than in A. arenosa are consistent with the repression of many genes that are expressed at higher levels in A. thaliana than in A. arenosa in the resynthesized allotetraploids. Moreover, non-CG (CC) methylation in the promoter region of A. thaliana At2g23810 remained in the resynthesized allotetraploids, and the methylation spread within the promoter region in natural A. suecica, leading to silencing of At2g23810. At2g23810 was demethylated and reactivated in met1-RNAi A. suecica lines. We suggest that many A. thaliana genes are transcriptionally repressed in resynthesized allotetraploids, and a subset of A. thaliana loci including transposons and centromeric repeats are heavily methylated and subjected to homeologous genome-specific RNA-mediated DNA methylation in natural allopolyploids.
- Published
- 2008
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30. Subjective definitions of tension.
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Cram JR and Lackey E
- Subjects
- Arm physiology, Humans, Leg physiology, Manifest Anxiety Scale, Muscles physiology, Tendons physiology, Muscle Contraction, Physical Exertion, Proprioception
- Abstract
To examine the type of proprioceptive information which subjects include in the definition of tension, 52 subjects were asked to indicate the location of where they felt tension while engaging in a simple motor task. Responses indicated that tendon stretch, muscle tension, and other cues are utilized in the subject's definition of tension.
- Published
- 1976
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31. Effectiveness of iodine for the disinfection of swimming pool water.
- Author
-
BLACK AP, LACKEY JB, and LACKEY EW
- Subjects
- Disinfection, Iodides, Iodine chemistry, Swimming Pools microbiology, Water
- Published
- 1959
- Full Text
- View/download PDF
Catalog
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