472 results on '"Kahr P"'
Search Results
2. Facet-Dependent Lethality of a Contact Insecticide Crystal.
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Yang, Jingxiang, Zhang, Chunfeng, Zhu, Xiaolong, Erriah, Bryan, Qiu, Mengdi, Ward, Michael D., and Kahr, Bart
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- 2024
- Full Text
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3. Facet-Dependent Lethality of a Contact Insecticide Crystal
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Yang, Jingxiang, Zhang, Chunfeng, Zhu, Xiaolong, Erriah, Bryan, Qiu, Mengdi, Ward, Michael D., and Kahr, Bart
- Abstract
The activity of crystalline contact insecticides relies on the extraction of surface molecules by insect tarsi upon contact. Most crystals are inherently anisotropic, and surface molecules on symmetry independent faces are expected to have different free energies. The facet-dependent bioavailability and associated efficacy of insect lethality have not been investigated, however. We discriminate the bioactivity of various facets of single crystals of DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane), a well-known contact insecticide. Our findings reveal facet-dependent lethality differences of nearly 75% among four crystallographically unique facets. Furthermore, computations reveal that the respective lethalities of the facets are strongly correlated with the detachment energies of molecules from the crystal surfaces. This facet-dependent lethality suggests a pathway to enhance the efficacy of known contact insecticides through crystal habit control.
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- 2024
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4. Acidification of α-granules in megakaryocytes by vacuolar-type adenosine triphosphatase is essential for organelle biogenesis
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Lu, Chien-Yi, Wu, Jing Ze, Yao, Helen H.Y., Liu, Richard J.Y., Li, Ling, Pluthero, Fred G., Freeman, Spencer A., and Kahr, Walter H.A.
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Platelets coordinate blood coagulation at sites of vascular injury and play fundamental roles in a wide variety of (patho)physiological processes. Key to many platelet functions is the transport and secretion of proteins packaged within α-granules, organelles produced by platelet precursor megakaryocytes. Prominent among α-granule cargo are fibrinogen endocytosed from plasma and endogenously synthesized von Willebrand factor. These and other proteins are known to require acidic pH for stable packaging. Luminal acidity has been confirmed for mature α-granules isolated from platelets, but direct measurement of megakaryocyte granule acidity has not been reported.
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- 2024
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5. Polymer-Assisted Polymorph Transition in Melt-Processed Molecular Semiconductor Crystals.
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Sundaram, Pallavi, Spencer, Rochelle B., Tiwari, Akash, Whittaker, St. John, Mandal, Trinanjana, Yang, Yongfan, Holland, Emma K., Kingsbury, Christopher J., Klopfenstein, Mia, Anthony, John E., Kahr, Bart, Jeong, Sehee, Shtukenberg, Alexander G., and Lee, Stephanie S.
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- 2024
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6. ROY Crystallization on Poly(ethylene) Fibers, a Model for Bed Net Crystallography.
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Erriah, Bryan, Shtukenberg, Alexander G., Aronin, Reese, McCarthy, Derik, Brázda, Petr, Ward, Michael D., and Kahr, Bart
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- 2024
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7. Chlorfenapyr Crystal Polymorphism and Insecticidal Activity.
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Aronin, Reese, Brázda, Petr, Smith, Leilani N., Zhang, Carolyn Jin, Benedict, Jason B., Marr, Zoe Y., Rybtchinski, Boris, Weissman, Haim, Shtukenberg, Alexander G., and Kahr, Bart
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- 2024
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8. Coherence in Polycrystalline Thin Films of Twisted Molecular Crystals.
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Yang, Yongfan, Shtukenberg, Alexander G., Zhou, Hengyu, Ruzie, Christian, Geerts, Yves Henri, Lee, Stephanie S., and Kahr, Bart
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- 2024
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9. Leveling up Organic Semiconductors with Crystal Twisting.
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Whittaker, St. John, Zhou, Hengyu, Spencer, Rochelle B., Yang, Yongfan, Tiwari, Akash, Bendesky, Justin, McDowell, Merritt, Sundaram, Pallavi, Lozano, Idalys, Kim, Shin, An, Zhihua, Shtukenberg, Alexander G., Kahr, Bart, and Lee, Stephanie S.
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- 2024
- Full Text
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10. ROY Crystallization on Poly(ethylene) Fibers, a Model for Bed Net Crystallography
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Erriah, Bryan, Shtukenberg, Alexander G., Aronin, Reese, McCarthy, Derik, Brázda, Petr, Ward, Michael D., and Kahr, Bart
- Abstract
Many long-lasting insecticidal bed nets for protection against disease vectors consist of poly(ethylene) fibers in which insecticide is incorporated during manufacture. Insecticide molecules diffuse from within the supersaturated polymers to surfaces where they become bioavailable to insects and often crystallize, a process known as blooming. Recent studies revealed that contact insecticides can be highly polymorphic. Moreover, insecticidal activity is polymorph-dependent, with forms having a higher crystal free energy yielding faster insect knockdown and mortality. Consequently, the crystallographic characterization of insecticide crystals that form on fibers is critical to understanding net function and improving net performance. Structural characterization of insecticide crystals on bed net fiber surfaces, let alone their polymorphs, has been elusive owing to the minute size of the crystals, however. Using the highly polymorphous compound ROY (5-methyl-2-[(2-nitrophenyl)-amino]thiophene-3-carbonitrile) as a proxy for insecticide crystallization, we investigated blooming and crystal formation on the surface of extruded poly(ethylene) fibers containing ROY. The blooming rates, tracked from the time of extrusion, were determined by UV–vis spectroscopy after successive washes. Six crystalline polymorphs (of the 13 known) were observed on poly(ethylene) fiber surfaces, and they were identified and characterized by Raman microscopy, scanning electron microscopy, and 3D electron diffraction. These observations reveal that the crystallization and phase behavior of polymorphs forming on poly(ethylene) fibers is complex and dynamic. The characterization of blooming and microcrystals underscores the importance of bed net crystallography for the optimization of bed net performance.
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- 2024
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11. Chlorfenapyr Crystal Polymorphism and Insecticidal Activity
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Aronin, Reese, Brázda, Petr, Smith, Leilani N., Zhang, Carolyn Jin, Benedict, Jason B., Marr, Zoe Y., Rybtchinski, Boris, Weissman, Haim, Shtukenberg, Alexander G., and Kahr, Bart
- Abstract
Four crystalline polymorphs of the proinsecticide chlorfenapyr [4-bromo-2-(4-chlorophenyl)-1-ethoxymethyl-5-trifluoromethyl-1H-pyrrole-3-carbonitrile] have been identified and characterized by polarized light optical microscopy, differential scanning calorimetry, Raman spectroscopy, X-ray diffraction, and electron diffraction. Three of the four structures were considered polytypic. Chlorfenapyr polymorphs show similar lethality against fruit flies (Drosophila melanogaster) and mosquitoes (Anopheles quadrimaculatus) with the least stable polymorph showing slightly higher lethality. Similar activities may be expected to be consistent with structural similarities. Knockdown kinetics, however, depend on an internal metabolic activating step, which further complicates polymorph-dependent bioavailability.
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- 2024
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12. Leveling up Organic Semiconductors with Crystal Twisting
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Whittaker, St. John, Zhou, Hengyu, Spencer, Rochelle B., Yang, Yongfan, Tiwari, Akash, Bendesky, Justin, McDowell, Merritt, Sundaram, Pallavi, Lozano, Idalys, Kim, Shin, An, Zhihua, Shtukenberg, Alexander G., Kahr, Bart, and Lee, Stephanie S.
- Abstract
The performance of crystalline organic semiconductors depends on the solid-state structure, especially the orientation of the conjugated components with respect to device platforms. Often, crystals can be engineered by modifying chromophore substituents through synthesis. Meanwhile, dissymetry is necessary for high-tech applications like chiral sensing, optical telecommunications, and data storage. The synthesis of dissymmetric molecules is a labor-intensive exercise that might be undermined because common processing methods offer little control over orientation. Crystal twisting has emerged as a generalizable method for processing organic semiconductors and offers unique advantages, such as patterning of physical and chemical properties and chirality that arises from mesoscale twisting. The precession of crystal orientations can enrich performance because achiral molecules in achiral space groups suddenly become candidates for the aforementioned technologies that require dissymetry.
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- 2024
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13. Self-Patterning Tetrathiafulvalene Crystalline Films.
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Whittaker, St. John, McDowell, Merritt, Bendesky, Justin, An, Zhihua, Yang, Yongfan, Zhou, Hengyu, Zhang, Yuze, Shtukenberg, Alexander G., Kalyon, Dilhan M., Kahr, Bart, and Lee, Stephanie S.
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- 2023
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14. Self-Patterning Tetrathiafulvalene Crystalline Films
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Whittaker, St. John, McDowell, Merritt, Bendesky, Justin, An, Zhihua, Yang, Yongfan, Zhou, Hengyu, Zhang, Yuze, Shtukenberg, Alexander G., Kalyon, Dilhan M., Kahr, Bart, and Lee, Stephanie S.
- Abstract
Tetrathiafulvalene (TTF) crystals grown from the melt are organized as spherulites in which helicoidal fibrils growing radially from the nucleation center twist in concert with one another. Alternating bright and dark concentric bands are apparent when films are viewed between crossed polarizers, indicating an alternating pattern of crystallographic faces exposed at the film surface. Band-dependent reorganization of the TTF crystals was observed during exposure to methanol vapor. Crystalline growth appears on bright bands at the expense of the dark bands. After a 24 h period of exposure to methanol vapor, the original spherulites were completely restructured, and the films comprise isolated, concentric circles of crystallites whose orientations are determined by the initial TTF crystal fibril orientation. While the surface of these outgrowths appears faceted and smooth, cross-sectional SEM images revealed a semiporous inner structure, suggesting solvent-vapor-induced recrystallization. Collectively, these results show that crystal twisting can be used to rhythmically redistribute material. Crystal twisting is a common and often controllable phenomenon independent of molecular or crystal structure and therefore offers a generalizable path to spontaneous pattern formation in a wide range of materials.
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- 2023
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15. Cold-stored platelets for acute bleeding in cardiac surgical patients: a narrative review
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Lu, Justin, Karkouti, Keyvan, Peer, Miki, Englesakis, Marina, Spinella, Philip C., Apelseth, Torunn O., Scorer, Thomas G., Kahr, Walter H. A., McVey, Mark, Rao, Vivek, Abrahamyan, Lusine, Lieberman, Lani, Mewhort, Holly, Devine, Dana V., Callum, Jeannie, and Bartoszko, Justyna
- Abstract
Purpose: Cold-stored platelets (CSP) are an increasingly active topic of international research. They are maintained at 1–6 °C, in contrast to standard room-temperature platelets (RTP) kept at 20–24 °C. Recent evidence suggests that CSP have superior hemostatic properties compared with RTP. This narrative review explores the application of CSP in adult cardiac surgery, summarizes the preclinical and clinical evidence for their use, and highlights recent research. Source: A targeted search of MEDLINE and other databases up to 24 February 2022 was conducted. Search terms combined concepts such as cardiac surgery, blood, platelet, and cold-stored. Searches of trial registries ClinicalTrials.gov and WHO International Clinical Trials Registry Platform were included. Articles were included if they described adult surgical patients as their population of interest and an association between CSP and clinical outcomes. References of included articles were hand searched. Principal findings: When platelets are stored at 1–6 °C, their metabolic rate is slowed, preserving hemostatic function for increased storage duration. Cold-stored platelets have superior adhesion characteristics under physiologic shear conditions, and similar or superior aggregation responses to physiologic agonists. Cold-stored platelets undergo structural, metabolic, and molecular changes which appear to “prime” them for hemostatic activity. While preliminary, clinical evidence supports the conduct of trials comparing CSP with RTP for patients with platelet-related bleeding, such as those undergoing cardiac surgery. Conclusion: Cold-stored platelets may have several advantages over RTP, including increased hemostatic capacity, extended shelf-life, and reduced risk of bacterial contamination. Large clinical trials are needed to establish their potential role in the treatment of acutely bleeding patients.
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- 2023
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16. GÖÇ, SINIF VE ÖRGÜT: TÜRKİYE’DE İŞÇİ SENDİKALARI VE SURİYELİ GÖÇMEN İŞÇİLER.
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KAHRAMAN, Fatma Bilge and KAHR, Alter
- Subjects
EMIGRATION & immigration ,MIGRANT labor ,SYRIANS ,IMMIGRANTS - Abstract
Copyright of Iş, Güç: The Journal of Industrial Relations & Human Resources is the property of Is, Guc: The Journal of Industrial Relations & Human Resources and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2023
17. Extracting Pure Circular Dichroism from Hierarchically Structured CdS Magic Cluster Films.
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Yao, Yuan, Ugras, Thomas J., Meyer, Talisi, Dykes, Matthew, Wang, Da, Arbe, Arantxa, Bals, Sara, Kahr, Bart, and Robinson, Richard D.
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- 2022
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18. One step closer but still far from solving the puzzle – The phylogeny of marine associated mites (Acari, Oribatida, Ameronothroidea) inferred from morphological and molecular genetic data
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Pfingstl, Tobias, Bardel-Kahr, Iris, and Schliep, Klaus
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- 2023
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19. Human ITGAV variants are associated with immune dysregulation, brain abnormalities, and colitis
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Ghasempour, Sina, Warner, Neil, Guan, Rei, Rodari, Marco M., Ivanochko, Danton, Whittaker Hawkins, Ryder, Marwaha, Ashish, Nowak, Jan K., Liang, Yijing, Mulder, Daniel J., Stallard, Lorraine, Li, Michael, Yu, Daniel D., Pluthero, Fred G., Batura, Vritika, Zhao, Mo, Siddiqui, Iram, Upton, Julia E.M., Hulst, Jessie M., Kahr, Walter H.A., Mendoza-Londono, Roberto, Charbit-Henrion, Fabienne, Hoefsloot, Lies H., Khiat, Anis, Moreira, Diana, Trindade, Eunice, Espinheira, Maria do Céu, Pinto Pais, Isabel, Weerts, Marjolein J.A., Douben, Hannie, Kotlarz, Daniel, Snapper, Scott B., Klein, Christoph, Dowling, James J., Julien, Jean-Philippe, Joosten, Marieke, Cerf-Bensussan, Nadine, Freeman, Spencer A., Parlato, Marianna, van Ham, Tjakko J., and Muise, Aleixo M.
- Abstract
Integrin heterodimers containing an Integrin alpha V subunit are essential for development and play critical roles in cell adhesion and signaling. We identified biallelic variants in the gene coding for Integrin alpha V (ITGAV) in three independent families (two patients and four fetuses) that either caused abnormal mRNA and the loss of functional protein or caused mistargeting of the integrin. This led to eye and brain abnormalities, inflammatory bowel disease, immune dysregulation, and other developmental issues. Mechanistically, the reduction of functional Integrin αV resulted in the dysregulation of several pathways including TGF-β–dependent signaling and αVβ3-regulated immune signaling. These effects were confirmed using immunostaining, RNA sequencing, and functional studies in patient-derived cells. The genetic deletion of itgav in zebrafish recapitulated patient phenotypes including retinal and brain defects and the loss of microglia in early development as well as colitis in juvenile zebrafish with reduced SMAD3 expression and transcriptional regulation. Taken together, the ITGAV variants identified in this report caused a previously unknown human disease characterized by brain and developmental defects in the case of complete loss-of-function and atopy, neurodevelopmental defects, and colitis in cases of incomplete loss-of-function.
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- 2024
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20. Extracting Pure Circular Dichroism from Hierarchically Structured CdS Magic Cluster Films
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Yao, Yuan, Ugras, Thomas J., Meyer, Talisi, Dykes, Matthew, Wang, Da, Arbe, Arantxa, Bals, Sara, Kahr, Bart, and Robinson, Richard D.
- Abstract
Chiroptically active, hierarchically structured materials are difficult to accurately characterize due to linear anisotropic contributions (i.e., linear dichroism (LD) and linear birefringence (LB)) and parasitic ellipticities that produce artifactual circular dichroism (CD) signals, in addition to chiral analyte contributions ranging from molecular-scale clusters to micron-sized assemblies. Recently, we have shown that CdS magic-sized clusters (MSC) can self-assemble into ordered films that have a hierarchical structure spanning seven orders of length-scale. These films have a strong CD response, but the chiral origins are obfuscated by the hierarchical architecture and LDLB contributions. Here, we derive and demonstrate a method for extracting the “pure” CD signal (CD generated by structural dissymmetry) from hierarchical MSC films and identified the chiral origin. The theory behind the method is derived using Mueller matrix and Stokes vector conventions and verified experimentally before being applied to hierarchical MSC and nanoparticle films with varying macroscopic orderings. Each film’s extracted “true CD” shares a bisignate profile aligned with the exciton peak, indicating the assemblies adopt a chiral arrangement and form an exciton coupled system. Interestingly, the linearly aligned MSC film possesses one of the highest g-factors (0.05) among semiconducting nanostructures reported. Additionally, we find that films with similar electronic transition dipole alignment can possess greatly different g-factors, indicating chirality change rather than anisotropy is the cause of the difference in the CD signal. The difference in g-factor is controllable via film evaporation geometry. This study provides a simple means to measure “true” CD and presents an example of experimentally understanding chiroptic interactions in hierarchical nanostructures.
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- 2022
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21. Efficient Polymorph Screening through Crystallization from Bulk and Confined Melts
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Fellah, Noalle, Tahsin, Lamia, Zhang, Carolyn Jin, Kahr, Bart, Ward, Michael D., and Shtukenberg, Alexander G.
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Crystallization from the melt can allow the achievement of high driving force for crystallization accompanied by relatively slow growth, nucleation, and transformation rates, features that favor its use as an efficient polymorph screening method. Surprisingly, even though melt crystallization has a long history, it has been employed less often in the search for new polymorphs than solution crystallization. Applications of melt crystallization to 21 highly polymorphic, well-characterized compounds with at least five ambient polymorphs revealed that melt crystallization afforded more than half of the known polymorphs and in many cases revealed new polymorphs not detected by other screening methods. A statistical analysis revealed that polymorphs grown from the melt have a greater propensity for high Z′ values, which are not easily accessible by other crystallization protocols and are often not detectable by crystal structure prediction methods. Melt crystallization within nanopores (8–100 nm) performed for 19 of the 21 compounds mostly resulted in polymorphs that dominated crystallization from the bulk melt at similar temperatures. The total number of polymorphs observed in nanopores was less than that observed during crystallization from the bulk melt, however, and melt crystallization under confinement revealed new polymorphs not detected by other crystallization methods.
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- 2022
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22. Transport in Twisted Crystalline Charge Transfer Complexes.
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Yang, Yongfan, Zhang, Yuze, Hu, Chunhua T., Sun, Mengmeng, Jeong, Sehee, Lee, Stephanie S., Shtukenberg, Alexander G., and Kahr, Bart
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- 2022
- Full Text
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23. Disrupting Crystal Growth through Molecular Recognition: Designer Therapies for Kidney Stone Prevention.
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Shtukenberg, Alexander G., Hu, Longqin, Sahota, Amrik, Kahr, Bart, and Ward, Michael D.
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- 2022
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24. Moderate-intensity aerobic exercise vs desmopressin in adolescent males with mild hemophilia A: a randomized trial
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Kumar, Riten, Dunn, Amy L., Schneiderman, Jane E., Gonzales, Anne, Bouskill, Vanessa, Widener, Pamela, Stanek, Joseph, Pluthero, Fred G., Waller, Amanda, Tarango, Cristina, Ahuja, Sanjay, Kerlin, Bryce A., Kahr, Walter H. A., Rand, Margaret L., Lillicrap, David, and Carcao, Manuel
- Abstract
Persons with mild hemophilia A (HA) may use intranasal desmopressin prior to sports participation. Desmopressin is expensive and can cause vomiting, headache, palpitation, and occasionally seizures. Our group has previously documented a 2.3-fold increase in factor VIII activity (FVIII:C) in adolescents with mild HA after moderate-intensity aerobic exercise. Herein, we report principal findings of a randomized trial of intranasal desmopressin vs a standardized, moderate-intensity aerobic exercise regimen in adolescents with mild HA. Our primary objective was to compare the change in FVIII:C associated with these 2 interventions. We also examined changes in hemostatic parameters arising from their sequential administration. The study was conducted simultaneously at the Hospital for Sick Children, Canada, and Nationwide Children’s Hospital, USA. Thirty-two eligible male adolescents (mean age ± standard deviation: 16.1 ± 2.6 years) with mild HA (mean baseline FVIII:C: 27.9% ± 18.4%) were randomized to 1 of 4 study arms (desmopressin followed by exercise, desmopressin alone, exercise followed by desmopressin, and exercise alone). Blood work was obtained at baseline and at 3 subsequent time-points. Participants randomized to exercise cycled on an ergometer for approximately 12 minutes, with the final 3 minutes at 85% of their predicted maximum heart rate. Standard weight-based dosing of desmopressin was used. Mean immediate increase in FVIII:C was 1.7-fold with exercise compared with 1.9-fold with desmopressin (noninferiority, P = .04). Exercise-induced improvement in hemostatic parameters including FVIII:C was brief compared with more sustained improvements seen with desmopressin. More than 60% of participants randomized to receive both exercise and desmopressin achieved normal (>50%) FVIII:C, 75 and 135 minutes into the study protocol.
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- 2022
- Full Text
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25. Moderate-intensity aerobic exercise vs desmopressin in adolescent males with mild hemophilia A: a randomized trial
- Author
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Kumar, Riten, Dunn, Amy L., Schneiderman, Jane E., Gonzales, Anne, Bouskill, Vanessa, Widener, Pamela, Stanek, Joseph, Pluthero, Fred G., Waller, Amanda, Tarango, Cristina, Ahuja, Sanjay, Kerlin, Bryce A., Kahr, Walter H.A., Rand, Margaret L., Lillicrap, David, and Carcao, Manuel
- Abstract
Persons with mild hemophilia A (HA) may use intranasal desmopressin prior to sports participation. Desmopressin is expensive and can cause vomiting, headache, palpitation, and occasionally seizures. Our group has previously documented a 2.3-fold increase in factor VIII activity (FVIII:C) in adolescents with mild HA after moderate-intensity aerobic exercise. Herein, we report principal findings of a randomized trial of intranasal desmopressin vs a standardized, moderate-intensity aerobic exercise regimen in adolescents with mild HA. Our primary objective was to compare the change in FVIII:C associated with these 2 interventions. We also examined changes in hemostatic parameters arising from their sequential administration. The study was conducted simultaneously at the Hospital for Sick Children, Canada, and Nationwide Children's Hospital, USA. Thirty-two eligible male adolescents (mean age ± standard deviation: 16.1 ± 2.6 years) with mild HA (mean baseline FVIII:C: 27.9% ± 18.4%) were randomized to 1 of 4 study arms (desmopressin followed by exercise, desmopressin alone, exercise followed by desmopressin, and exercise alone). Blood work was obtained at baseline and at 3 subsequent time-points. Participants randomized to exercise cycled on an ergometer for approximately 12 minutes, with the final 3 minutes at 85% of their predicted maximum heart rate. Standard weight-based dosing of desmopressin was used. Mean immediate increase in FVIII:C was 1.7-fold with exercise compared with 1.9-fold with desmopressin (noninferiority, P= .04). Exercise-induced improvement in hemostatic parameters including FVIII:C was brief compared with more sustained improvements seen with desmopressin. More than 60% of participants randomized to receive both exercise and desmopressin achieved normal (>50%) FVIII:C, 75 and 135 minutes into the study protocol.
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- 2022
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26. Platelet VPS16B is dependent on VPS33B expression, as determined in two siblings with arthrogryposis, renal dysfunction, and cholestasis syndrome
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Penon‐Portmann, Monica, Westbury, Sarah K., Li, Ling, Pluthero, Fred G., Liu, Richard J.Y., Yao, Helen H.Y., Geng, Ryan S.Q., Warner, Neil, Muise, Aleixo M., Lotz‐Esquivel, Stephanie, Howell‐Ramirez, Marianela, Saborío‐Chacon, Pablo, Fernández‐Rojas, Sara, Saborio‐Rocafort, Manuel, Jiménez‐Hernández, Mildred, Wang‐Zuniga, Carolina, Cartín‐Sánchez, Walter, Shieh, Joseph T., Badilla‐Porras, Ramses, and Kahr, Walter H.A.
- Abstract
Platelet α‐granule biogenesis in precursor megakaryocytes is critically dependent on VPS33B and VPS16B, as demonstrated by the platelet α‐granule deficiency seen in the rare multisystem disorder arthrogryposis, renal dysfunction, and cholestasis (ARC) syndrome associated with biallelic pathogenic variants in VPS33Band VIPAS39(encoding VPS16B). VPS33B and VPS16B are ubiquitously expressed proteins that are known to interact and play key roles in protein sorting and trafficking between subcellular locations. However, there remain significant gaps in our knowledge of the nature of these interactions in primary cells from patients with ARC syndrome.
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- 2022
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27. Platelet VPS16B is dependent on VPS33B expression, as determined in two siblings with arthrogryposis, renal dysfunction, and cholestasis syndrome
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Penon‐Portmann, Monica, Westbury, Sarah K., Li, Ling, Pluthero, Fred G., Liu, Richard J. Y., Yao, Helen H. Y., Geng, Ryan S. Q., Warner, Neil, Muise, Aleixo M., Lotz‐Esquivel, Stephanie, Howell‐Ramirez, Marianela, Saborío‐Chacon, Pablo, Fernández‐Rojas, Sara, Saborio‐Rocafort, Manuel, Jiménez‐Hernández, Mildred, Wang‐Zuniga, Carolina, Cartín‐Sánchez, Walter, Shieh, Joseph T., Badilla‐Porras, Ramses, and Kahr, Walter H. A.
- Abstract
Platelet α‐granule biogenesis in precursor megakaryocytes is critically dependent on VPS33B and VPS16B, as demonstrated by the platelet α‐granule deficiency seen in the rare multisystem disorder arthrogryposis, renal dysfunction, and cholestasis (ARC) syndrome associated with biallelic pathogenic variants in VPS33Band VIPAS39(encoding VPS16B). VPS33B and VPS16B are ubiquitously expressed proteins that are known to interact and play key roles in protein sorting and trafficking between subcellular locations. However, there remain significant gaps in our knowledge of the nature of these interactions in primary cells from patients with ARC syndrome. To use primary cells from patients with ARC syndrome to better understand the interactions and roles of VPS33B and VPS16B in platelets and precursor megakaryocytes. The proband and his male sibling were clinically suspected to have ARC syndrome. Confirmatory genetic testing and platelet phenotyping, including electron microscopy and protein expression analysis, was performed with consent in a research setting. We describe the first case of ARC syndrome identified in Costa Rica, associated with a novel homozygous nonsense VPS33Bvariant that is linked with loss of expression of both VPS33B and VPS16B in platelets. These results indicate that stable expression of VPS16B in platelets, their precursor megakaryocytes, and other cells is dependent on VPS33B. We suggest that systematic evaluation of primary cells from patients with a range of VPS33Band VIPAS39variants would help to elucidate the interactions and functions of these proteins.
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- 2022
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28. Competing Singlet Fission and Excimer Formation in Solid Fluorinated 1,3-Diphenylisobenzofurans.
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Buchanan, Eric A., Johnson, Justin C., Tan, Melissa, Kaleta, Jiří, Shtukenberg, Alexander G., Bateman, Gage, Benedict, Jason B., Shinjiro Kobayashi, Jin Wen, Bart Kahr, Císařová, Ivana, and Michl, Josef
- Published
- 2021
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29. Imidacloprid Crystal Polymorphs for Disease Vector Control and Pollinator Protection.
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Zhu, Xiaolong, Hu, Chunhua T., Erriah, Bryan, Vogt-Maranto, Leslie, Yang, Jingxiang, Yang, Yongfan, Qiu, Mengdi, Fellah, Noalle, Tuckerman, Mark E., Ward, Michael D., and Kahr, Bart
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- 2021
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30. The association of thrombin generation with bleeding outcomes in cardiac surgery: a prospective observational study
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Bartoszko, Justyna, Li, Han, Fitzgerald, John, Ho, Loretta T. S., Serrick, Cyril, Kahr, Walter H. A., Gross, Peter L., and Karkouti, Keyvan
- Abstract
Background: Cardiac surgery with cardiopulmonary bypass (CPB) is associated with coagulopathic bleeding. Impaired thrombin generation may be an important cause of coagulopathic bleeding but is poorly measured by existing hemostatic assays. We examined thrombin generation during cardiac surgery, using calibrated automated thrombography, and its association with bleeding outcomes. Methods: We conducted a prospective observational study in 100 patients undergoing cardiac surgery with CPB. Calibrated automated thrombography parameters were expressed as a ratio of post-CPB values divided by pre-CPB values. The association of thrombin generation parameters for bleeding outcomes was compared with conventional tests of hemostasis, and the outcomes of patients with the most severe post-CPB impairment in thrombin generation (≥ 80% drop from baseline) were compared with the rest of the cohort. Results: All 100 patients were included in the final analysis, with a mean age of 63 (12) yr, 31 (31%) female, and 94 (94%) undergoing bypass and/or valve surgery. Post-CPB, peak thrombin decreased by a median of 73% (interquartile range [IQR], 49–91%) (P< 0.001) and total thrombin generation, expressed as the endogenous thrombin potential (ETP), decreased 56% [IQR, 30–83%] (P< 0.001). In patients with ≥ 80% decrease in ETP, 21% required re-exploration for bleeding compared with 7% in the rest of the cohort (P= 0.04), and 48% required medical or surgical treatment for hemostasis compared with 27% in the rest of the cohort (P= 0.04). Conclusions: Thrombin generation is significantly impaired by CPB and associated with higher bleeding severity. Clinical studies aimed at the identification and treatment of patients with impaired thrombin generation are warranted.
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- 2022
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31. Transport in Twisted Crystalline Charge Transfer Complexes
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Yang, Yongfan, Zhang, Yuze, Hu, Chunhua T., Sun, Mengmeng, Jeong, Sehee, Lee, Stephanie S., Shtukenberg, Alexander G., and Kahr, Bart
- Abstract
Many crystals grow as banded spherulites from the melt with an optical rhythm indicative of helicoidal twisting. In this work, 23 of 41 charge transfer complexes (CTCs) are grown with twisted morphologies. As a group, CTCs more commonly twist (56%) than molecular crystals arbitrarily chosen in our previous research (31%). To analyze the effect of twisting on charge transport, three tetracyanoethylene-based CTCs with phenanthrene (PhT), pyrene (PyT), and perylene are characterized. PhT and PyT are subject to mobility measurements using organic field-effect transistors. The mobilities for twisted crystals are around three times higher than for crystals with no ostensible optical modulation, which are effectively straight. The differences in mobilities of straight and twisted crystals are considered computationally based on density functional theory. Straight crystal models built from crystallographic information files are calculated and present anisotropic hole and electron transport. For twisted crystal models, adjacent layers in the supercell are rotated by 0.01° around experimentally determined twisting directions. The modified transfer integrals lead to a slight increase (up to 25%) in the calculated mobilities of twisted crystals. Comparisons of model calculations on individual fibrils and measurements of ensembles of fibrils indicate that interfaces between single crystals are likely consequential.
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- 2022
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32. Disrupting Crystal Growth through Molecular Recognition: Designer Therapies for Kidney Stone Prevention
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Shtukenberg, Alexander G., Hu, Longqin, Sahota, Amrik, Kahr, Bart, and Ward, Michael D.
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Aberrant crystallization within the human body can lead to several disease states or adverse outcomes, yet much remains to be understood about the critical stages leading to these events, which can include crystal nucleation and growth, crystal aggregation, and the adhesion of crystals to cells. Kidney stones, which are aggregates of single crystals with physiological origins, are particularly illustrative of pathological crystallization, with 10% of the U.S. population experiencing at least one stone occurrence in their lifetimes. The human record of kidney stones is more than 2000 years old, as noted by Hippocrates in his renowned oath and much later by Robert Hooke in his treatise Micrographia. William Hyde Wollaston, who was a physician, chemist, physicist, and crystallographer, was fascinated with stones, leading him to discover an unusual stone that he described in 1810 as cystic oxide, later corrected to cystine. Despite this long history, however, a fundamental understanding of the stages of stone formation and the rational design of therapies for stone prevention have remained elusive.
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- 2022
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33. Habitual Physical Activity in Patients with Myasthenia Gravis Assessed by Accelerometry and Questionnaire
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Andersen, Linda Kahr and Vissing, John
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Background: Physical activity (PA) in patients with myasthenia gravis (MG) is considered safe and beneficial, and an active lifestyle is required to obtain the health benefits of exercise. However, as the disease leads to physical impairments an insight into the overall PA habits in this patient population is relevant but lacking.Objective: To measure habitual physical activity in a Danish cohort of patients with MG measured by accelerometer and questionnaire, and to determine relevant predictors for PA intensities.Methods: Habitual physical activity was assessed by; 1) the accelerometer ActiGraphin a cohort of patients recruited from our neuromuscular clinic, 2) the International Physical Activity Questionnaire(IPAQ) in a web-based survey. PA levels were compared to international recommendations. Predictors for PA (age, sex, body mass index, disease severity and duration) were included in the regression analyses.Results: Habitual physical activity was measured by accelerometer for 7 days in 69 patients and by questionnaire in 691 patients. Measured by the accelerometer, 46%of the patients did not meet the international recommendations for PA at moderate/vigorous intensity and 57%were below the recommendations for steps per day. Measured by the IPAQ, 48%did not meet the recommendations. Disease severity and age were predictors for PA intensities.Conclusions: This study found that around half of the included patients did not meet the recommendations for PA. This is a concern, as it increases the risk of life-style related diseases. Disease severity and age may be taking into consideration when counseling the patients about PA.
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- 2022
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34. Competing Singlet Fission and Excimer Formation in Solid Fluorinated 1,3-Diphenylisobenzofurans
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Buchanan, Eric A., Johnson, Justin C., Tan, Melissa, Kaleta, Jiří, Shtukenberg, Alexander G., Bateman, Gage, Benedict, Jason B., Kobayashi, Shinjiro, Wen, Jin, Kahr, Bart, Císařová, Ivana, and Michl, Josef
- Abstract
Singlet fission (kSF) and excimer formation (kEXC) rate constants along with other photophysical properties of thin solid layers of 1,3-diphenylisobenzofuran and 11 of its fluorinated derivatives have been determined. The molecular properties of these compounds are similar, but their crystal packing varies widely. Most of them undergo singlet fission whereas excitation in others is trapped in excimers. The trend in rate constants kSFagrees qualitatively with results of calculations by a simplified version of the frontier orbital model for a molecular pair. The main shortcoming of the model is discussed.
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- 2021
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35. Immune cells surveil aberrantly sialylated O-glycans on megakaryocytes to regulate platelet count
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Lee-Sundlov, Melissa M., Burns, Robert T., Kim, Taylor O., Grozovsky, Renata, Giannini, Silvia, Rivadeneyra, Leonardo, Zheng, Yongwei, Glabere, Simon H., Kahr, Walter H. A., Abdi, Reza, Despotovic, Jenny M., Wang, Demin, and Hoffmeister, Karin M.
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Immune thrombocytopenia (ITP) is a platelet disorder. Pediatric and adult ITP have been associated with sialic acid alterations, but the pathophysiology of ITP remains elusive, and ITP is often a diagnosis of exclusion. Our analysis of pediatric ITP plasma samples showed increased anti–Thomsen-Friedenreich antigen (TF antigen) antibody representation, suggesting increased exposure of the typically sialylated and cryptic TF antigen in these patients. The O-glycan sialyltransferase St3gal1 adds sialic acid specifically on the TF antigen. To understand if TF antigen exposure associates with thrombocytopenia, we generated a mouse model with targeted deletion of St3gal1 in megakaryocytes (MK) (St3gal1MK−
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- 2021
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36. Immune cells surveil aberrantly sialylated O-glycans on megakaryocytes to regulate platelet count
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Lee-Sundlov, Melissa M., Burns, Robert T., Kim, Taylor O., Grozovsky, Renata, Giannini, Silvia, Rivadeneyra, Leonardo, Zheng, Yongwei, Glabere, Simon H., Kahr, Walter H.A., Abdi, Reza, Despotovic, Jenny M., Wang, Demin, and Hoffmeister, Karin M.
- Abstract
Immune thrombocytopenia (ITP) is a platelet disorder. Pediatric and adult ITP have been associated with sialic acid alterations, but the pathophysiology of ITP remains elusive, and ITP is often a diagnosis of exclusion. Our analysis of pediatric ITP plasma samples showed increased anti–Thomsen-Friedenreich antigen (TF antigen) antibody representation, suggesting increased exposure of the typically sialylated and cryptic TF antigen in these patients. The O-glycan sialyltransferase St3gal1adds sialic acid specifically on the TF antigen. To understand if TF antigen exposure associates with thrombocytopenia, we generated a mouse model with targeted deletion of St3gal1in megakaryocytes (MK) (St3gal1MK−/−). TF antigen exposure was restricted to MKs and resulted in thrombocytopenia. Deletion of Jak3 in St3gal1MK−/−mice normalized platelet counts implicating involvement of immune cells. Interferon-producing Siglec H–positive bone marrow (BM) immune cells engaged with O-glycan sialic acid moieties to regulate type I interferon secretion and platelet release (thrombopoiesis), as evidenced by partially normalized platelet count following inhibition of interferon and Siglec H receptors. Single-cell RNA-sequencing determined that TF antigen exposure by MKs primed St3gal1MK−/−BM immune cells to release type I interferon. Single-cell RNA-sequencing further revealed a new population of immune cells with a plasmacytoid dendritic cell–like signature and concomitant upregulation of the immunoglobulin rearrangement gene transcripts Igkc and Ighm, suggesting additional immune regulatory mechanisms. Thus, aberrant TF antigen moieties, often found in pathological conditions, regulate immune cells and thrombopoiesis in the BM, leading to reduced platelet count.
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- 2021
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37. Imidacloprid Crystal Polymorphs for Disease Vector Control and Pollinator Protection
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Zhu, Xiaolong, Hu, Chunhua T., Erriah, Bryan, Vogt-Maranto, Leslie, Yang, Jingxiang, Yang, Yongfan, Qiu, Mengdi, Fellah, Noalle, Tuckerman, Mark E., Ward, Michael D., and Kahr, Bart
- Abstract
Imidacloprid, the world’s leading insecticide, has been approved recently for controlling infectious disease vectors; yet, in agricultural settings, it has been implicated in the frightening decline of pollinators. This argues for strategies that sharply reduce the environmental impact of imidacloprid. When used as a contact insecticide, the effectiveness of imidacloprid relies on physical contact between its crystal surfaces and insect tarsi. Herein, seven new imidacloprid crystal polymorphs are reported, adding to two known forms. Anticipating that insect uptake of imidacloprid molecules would depend on the respective free energies of crystal polymorph surfaces, measurements of insect knockdown times for the metastable crystal forms were as much as nine times faster acting than the commercial form against Aedes, Anopheles, and Culexmosquitoes as well as Drosophila(fruit flies). These results suggest that replacement of commercially available imidacloprid crystals (a.k.a. Form I) in space-spraying with any one of three new polymorphs, Forms IV, VI, IX, would suppress vector-borne disease transmission while reducing environmental exposure and harm to nontarget organisms.
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- 2021
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38. Punin Ripening and the Classification of Solution-Mediated Recrystallization Mechanisms.
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Shtukenberg, Alexander G., García-Ruiz, Juan Manuel, and Kahr, Bart
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- 2021
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39. Highly Polymorphous Nicotinamide and Isonicotinamide: Solution versus Melt Crystallization
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Fellah, Noalle, Zhang, Carolyn Jin, Chen, Catherine, Hu, Chunhua T., Kahr, Bart, Ward, Michael D., and Shtukenberg, Alexander G.
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The crystallization of nicotinamide (NA) and its constitutional isomer, isonicotinamide (INA), is compared. NA formed eight polymorphs from the melt and two from solution, whereas INA formed two polymorphs from the melt and six from solution. This analysis was provoked by the observation that NA is highly polymorphic from the melt, while the closely related INA is highly polymorphous from solution. A combination of hot stage polarized light microscopy, powder X-ray diffraction, and Raman spectroscopy revealed that the polymorph selectivities are not related to supramolecular self-association in the growth media. The larger estimated free energy gap separating NA polymorphs, compared with that of the INA polymorphs, is consistent with the smaller number of NA polymorphs generated from solution. Phenomenological analyses of crystallization kinetics suggest that cross nucleation is the most likely reason more polymorphs of NA than INA crystallize from the melt.
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- 2021
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40. Inherited Platelet Disorders: Diagnosis and Management.
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Al-Huniti, Ahmad and Kahr, Walter HA
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Inherited platelet disorders are rare but they can have considerable clinical impacts, and studies of their causes have advanced understanding of platelet formation and function. Effective hemostasis requires adequate circulating numbers of functional platelets. Quantitative, qualitative and combined platelet disorders with a bleeding phenotype have been linked to defects in platelet cytoskeletal elements, cell surface receptors, signal transduction pathways, secretory granules and other aspects. Inherited platelet disorders have variable clinical presentations, and diagnosis and management is often challenging. Evaluation begins with detailed patient and family histories, including a bleeding score. The physical exam identifies potential syndromic features of inherited platelet disorders and rules out other causes. Laboratory investigations include a complete blood count, blood film, coagulation testing and Von Willebrand factor assessment. A suspected platelet function disorder is further assessed by platelet aggregation, flow cytometry, platelet dense granule release and/or content, and genetic testing. The management of platelet function disorders aims to minimize the risk of bleeding and achieve adequate hemostasis when needed. Although not universal, platelet transfusion remains a crucial component in the management of many inherited platelet disorders. • Inherited platelet function disorders are numerous and diverse. • Genomic methods have supported the identification and diagnosis of many new inherited platelet function disorders. • Bleeding in patients with inherited platelet disorders are is managed differently depending on the defect. • This review highlights well known and recently discovered inherited platelet disorders and their management. [ABSTRACT FROM AUTHOR]
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- 2020
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41. Common Occurrence of Twisted Molecular Crystal Morphologies from the Melt.
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Shtukenberg, Alexander G., Zhu, Xiaolong, Yang, Yongfan, and Kahr, Bart
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- 2020
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42. Why Are Some Crystals Straight?
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Li, Chao, Shtukenberg, Alexander G., Vogt-Maranto, Leslie, Efrati, Efi, Raiteri, Paolo, Gale, Julian D., Rohl, Andrew L., and Kahr, Bart
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- 2020
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43. The timing of venous thromboembolism in ovarian cancer patients: A nationwide Danish cohort study
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Strøm Kahr, Henriette, Christiansen, Ole B., Juul Riddersholm, Signe, Gade, Inger L., Torp‐Pedersen, Christian, Knudsen, Aage, and Thorlacius‐Ussing, Ole
- Abstract
Venous thromboembolism (VTE) is associated with excess mortality and morbidity in cancer, and is influenced by patient‐, tumor‐, and treatment‐related factors. We aimed to investigate the impact of such factors in a national cohort of patients with epithelial ovarian cancer (EOC).
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- 2021
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44. The timing of venous thromboembolism in ovarian cancer patients: A nationwide Danish cohort study
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Strøm Kahr, Henriette, Christiansen, Ole B., Juul Riddersholm, Signe, Gade, Inger L., Torp‐Pedersen, Christian, Knudsen, Aage, and Thorlacius‐Ussing, Ole
- Abstract
Venous thromboembolism (VTE) is associated with excess mortality and morbidity in cancer, and is influenced by patient‐, tumor‐, and treatment‐related factors. We aimed to investigate the impact of such factors in a national cohort of patients with epithelial ovarian cancer (EOC). Patients in the Danish Gynecologic Cancer Database (DGCD) with EOC from 2005 to 2014 were followed from time of diagnosis to VTE, or censoring. Surgery, chemotherapy, and vascular epithelial growth factor (VEGF)‐inhibitors were included as time‐varying exposures in Cox proportional hazard regression models. A total of 551 VTE events were registered in 4991 EOC patients. Median follow‐up time was 2.9 years. The 2‐year cumulative incidence of VTE was 7.2%. Patients were at highest risk during the first year after EOC diagnosis. Previous VTE was associated with a hazard ratio (HR) of 3.26 (95% confidence interval [CI] 2.42–4.39). Exposure to major pelvic surgery was associated with a HR of 3.21 (95% CI 2.29–4.50). Exposure to chemotherapy or (VEGF)‐inhibitors were associated with HRs of 1.91 (95% CI 1.56–2.33) and 1.05 (95% CI 0.57–1.93), respectively. Hazard ratios for patients with clear cell histopathology was 1.46 (95% CI 0.97–2.20) and 2.42 for International Federation of Gynaecology and Obstetrics stage III‐‐IV (95% CI 1.93–3.03). EOC is associated with a high risk of VTE, particularly within the first year after diagnosis. Major pelvic surgery and chemotherapy were strongly associated with VTE. Person‐related risk factors were increasing age and previous VTE. Advanced stage was an independent tumor‐related risk factor. These findings support the indication for thrombosis prophylaxis during chemotherapy.
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- 2021
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45. Punin Ripening and the Classification of Solution-Mediated Recrystallization Mechanisms
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Shtukenberg, Alexander G., García-Ruiz, Juan Manuel, and Kahr, Bart
- Abstract
Ripening (also called recrystallization) is a process that occurs commonly in nature and industry that shifts the size distribution of an ensemble of crystals toward a smaller number of larger crystals. Ostwald ripening is by far the best known recrystallization mechanism and sometimes is mistakenly considered as the only mechanism for shifting the crystal size distribution. Ostwald ripening accounts for recrystallization under thermodynamic control and is driven only by the well-known size dependence of solubility. There are, however, other recrystallization mechanisms that can be observed on laboratory timescales for crystals of any size under certain conditions. Internal stress dispersion is a thermodynamic ripening mechanism that depends not on surface energies but rather on crystal defects. In addition, there are two other mechanisms that are kinetic in nature. The most efficient is driven by the size dependence of growth and dissolution rates at low supersaturation. Finally, a mechanism proposed by Punin is driven by the difference between growth and dissolution rates due to crystal defects. All the four mechanisms can be at work simultaneously. The efficiency of ripening can be enhanced by temperature oscillations, but only the thermodynamic mechanisms can work at constant temperature. In this paper, we discuss the fundamentals of these four ripening mechanisms and revisit in detail Punin’s mechanism because it is the least well articulated in the literature.
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- 2021
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46. Gray platelet syndrome: NBEAL2 mutations are associated with pathology beyond megakaryocyte and platelet function defects
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Pluthero, Fred G. and Kahr, Walter H. A.
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- 2021
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47. Gray platelet syndrome: NBEAL2 mutations are associated with pathology beyond megakaryocyte and platelet function defects
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Pluthero, Fred G. and Kahr, Walter H.A.
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- 2021
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48. Specifications of the variant curation guidelines for ITGA2B/ITGB3: ClinGen Platelet Disorder Variant Curation Panel
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Ross, Justyne E., Zhang, Bing M., Lee, Kristy, Mohan, Shruthi, Branchford, Brian R., Bray, Paul, Dugan, Stefanie N., Freson, Kathleen, Heller, Paula G., Kahr, Walter H.A., Lambert, Michele P., Luchtman-Jones, Lori, Luo, Minjie, Perez Botero, Juliana, Rondina, Matthew T., Ryan, Gabriella, Westbury, Sarah, Bergmeier, Wolfgang, and Di Paola, Jorge
- Abstract
Accurate and consistent sequence variant interpretation is critical to the correct diagnosis and appropriate clinical management and counseling of patients with inherited genetic disorders. To minimize discrepancies in variant curation and classification among different clinical laboratories, the American College of Medical Genetics and Genomics (ACMG), along with the Association for Molecular Pathology (AMP), published standards and guidelines for the interpretation of sequence variants in 2015. Because the rules are not universally applicable to different genes or disorders, the Clinical Genome Resource (ClinGen) Platelet Disorder Expert Panel (PD-EP) has been tasked to make ACMG/AMP rule specifications for inherited platelet disorders. ITGA2Band ITGB3, the genes underlying autosomal recessive Glanzmann thrombasthenia (GT), were selected as the pilot genes for specification. Eight types of evidence covering clinical phenotype, functional data, and computational/population data were evaluated in the context of GT by the ClinGen PD-EP. The preliminary specifications were validated with 70 pilot ITGA2B/ITGB3variants and further refined. In the final adapted criteria, gene- or disease-based specifications were made to 16 rules, including 7 with adjustable strength; no modification was made to 5 rules; and 7 rules were deemed not applicable to GT. Employing the GT-specific ACMG/AMP criteria to the pilot variants resulted in a reduction of variants classified with unknown significance from 29% to 20%. The overall concordance with the initial expert assertions was 71%. These adapted criteria will serve as guidelines for GT-related variant interpretation to increase specificity and consistency across laboratories and allow for better clinical integration of genetic knowledge into patient care.
- Published
- 2021
- Full Text
- View/download PDF
49. Specifications of the variant curation guidelines for ITGA2B/ITGB3: ClinGen Platelet Disorder Variant Curation Panel
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Ross, Justyne E., Zhang, Bing M., Lee, Kristy, Mohan, Shruthi, Branchford, Brian R., Bray, Paul, Dugan, Stefanie N., Freson, Kathleen, Heller, Paula G., Kahr, Walter H. A., Lambert, Michele P., Luchtman-Jones, Lori, Luo, Minjie, Perez Botero, Juliana, Rondina, Matthew T., Ryan, Gabriella, Westbury, Sarah, Bergmeier, Wolfgang, and Di Paola, Jorge
- Abstract
Accurate and consistent sequence variant interpretation is critical to the correct diagnosis and appropriate clinical management and counseling of patients with inherited genetic disorders. To minimize discrepancies in variant curation and classification among different clinical laboratories, the American College of Medical Genetics and Genomics (ACMG), along with the Association for Molecular Pathology (AMP), published standards and guidelines for the interpretation of sequence variants in 2015. Because the rules are not universally applicable to different genes or disorders, the Clinical Genome Resource (ClinGen) Platelet Disorder Expert Panel (PD-EP) has been tasked to make ACMG/AMP rule specifications for inherited platelet disorders. ITGA2B and ITGB3, the genes underlying autosomal recessive Glanzmann thrombasthenia (GT), were selected as the pilot genes for specification. Eight types of evidence covering clinical phenotype, functional data, and computational/population data were evaluated in the context of GT by the ClinGen PD-EP. The preliminary specifications were validated with 70 pilot ITGA2B/ITGB3 variants and further refined. In the final adapted criteria, gene- or disease-based specifications were made to 16 rules, including 7 with adjustable strength; no modification was made to 5 rules; and 7 rules were deemed not applicable to GT. Employing the GT-specific ACMG/AMP criteria to the pilot variants resulted in a reduction of variants classified with unknown significance from 29% to 20%. The overall concordance with the initial expert assertions was 71%. These adapted criteria will serve as guidelines for GT-related variant interpretation to increase specificity and consistency across laboratories and allow for better clinical integration of genetic knowledge into patient care.
- Published
- 2021
- Full Text
- View/download PDF
50. Habitual Physical Activity in Patients with Myasthenia Gravis Assessed by Accelerometry and Questionnaire
- Author
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Kahr Andersen, Linda and Vissing, John
- Abstract
Physical activity (PA) in patients with myasthenia gravis (MG) is considered safe and beneficial, and an active lifestyle is required to obtain the health benefits of exercise. However, as the disease leads to physical impairments an insight into the overall PA habits in this patient population is relevant but lacking. To measure habitual physical activity in a Danish cohort of patients with MG measured by accelerometer and questionnaire, and to determine relevant predictors for PA intensities. Habitual physical activity was assessed by; 1) the accelerometer Acti Graphin a cohort of patients recruited from our neuromuscular clinic, 2) the International Physical Activity Questionnaire(IPAQ) in a web-based survey. PA levels were compared to international recommendations. Predictors for PA (age, sex, body mass index, disease severity and duration) were included in the regression analyses. Habitual physical activity was measured by accelerometer for 7 days in 69 patients and by questionnaire in 691 patients. Measured by the accelerometer, 46%of the patients did not meet the international recommendations for PA at moderate/vigorous intensity and 57%were below the recommendations for steps per day. Measured by the IPAQ, 48%did not meet the recommendations. Disease severity and age were predictors for PA intensities. This study found that around half of the included patients did not meet the recommendations for PA. This is a concern, as it increases the risk of life-style related diseases. Disease severity and age may be taking into consideration when counseling the patients about PA.
- Published
- 2021
- Full Text
- View/download PDF
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