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Whalen NS, Hunt TC, Erickson GM. Evapotranspiration-linked silica deposition in a basal tracheophyte plant (Lycopodiaceae: Lycopodiella alopecuroides): implications for the evolutionary origins of phytoliths. New Phytol 2023; 238:2224-2235. [PMID: 36869439 DOI: 10.1111/nph.18861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 02/24/2023] [Indexed: 05/04/2023]
Abstract
Phytoliths, microscopic deposits of hydrated silica within plants, play a myriad of functional roles in extant tracheophytes - yet their evolutionary origins and the original selective pressures leading to their deposition remain poorly understood. To gain new insights into the ancestral condition of tracheophyte phytolith production and function, phytolith content was intensively assayed in a basal, morphologically conserved tracheophyte: the foxtail clubmoss Lycopodiella alopecuroides. Wet ashing was employed to perform phytolith extractions from every major anatomical region of L. alopecuroides. Phytolith occurrence was recorded, alongside abundance, morphometric information, and morphological descriptions. Phytoliths were recovered exclusively from the microphylls, which were apicodistally silicified into multiphytolith aggregates. Phytolith aggregates were larger and more numerous in anatomical regions engaging in greater evapotranspirational activity. The tissue distribution of L. alopecuroides phytoliths is inconsistent with the expectations of proposed adaptive hypotheses of phytolith evolutionary origin. Instead, it is hypothesized that phytoliths may have arisen incidentally in the L. alopecuroides-like ancestral plant, polymerizing from intraplant silicon accumulations arising via bulk flow and 'leaky' cellular micronutrient channels. This basal, nonadaptive phytolith formation model would provide the evolutionary 'raw material' for later modification into the useful, adaptative, phytolith deposits seen in later-diverging plant clades.
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Affiliation(s)
- Niall S Whalen
- Department of Biological Science, Florida State University, 319 Stadium Drive, Tallahassee, FL, 32304, USA
| | - Tyler C Hunt
- Department of Biological Science, Florida State University, 319 Stadium Drive, Tallahassee, FL, 32304, USA
| | - Gregory M Erickson
- Department of Biological Science, Florida State University, 319 Stadium Drive, Tallahassee, FL, 32304, USA
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Hunt TC, Grejtak T, Kodangal D, Varma S, Rinaldi CE, Pathak S, Krick BA, Erickson GM. Microstructurally driven self-sharpening mechanism in beaver incisor enamel facilitates their capacity to fell trees. Acta Biomater 2023; 158:412-422. [PMID: 36603731 DOI: 10.1016/j.actbio.2022.12.051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 12/06/2022] [Accepted: 12/22/2022] [Indexed: 01/04/2023]
Abstract
Beavers (Castor) stand out among mammals for their unique capacity to fell trees using their large, ever-growing incisors. This routine consumption of resistant fodder induces prodigious wear in the lower incisors, despite this blunting effect the incisors maintain a remarkably sharp cutting edge. Notably, the enamel edges of their incisors show a highly complex two-part microstructure of which the biomechanical import is unknown. Here, using fracture analysis, nanoindentation, and wear testing on North American beaver (C. canadensis) incisors we test the microstructure's possible contribution to maintaining incisal sharpness. Although comparable in hardness, the inner enamel preferentially fails and readily wears at 2.5 times the rate of the outer enamel. The outer microstructure redirects all fractures in parallel, decreasing fracture coalescence. Conversely, the inner microstructure facilitates crack coalescence increasing the wear rate by isolating layers of enamel prisms that readily fragment. Together these two architectures form a microstructurally driven self-sharpening mechanism contained entirely within the thin enamel shell. Our results demonstrate that enamel microstructures exposed at the occlusal surface can markedly influence both enamel crest shape and surface texture in wearing dentitions. The methods introduced here open the door to exploring the biomechanical functionality and evolution of enamel microstructures throughout Mammalia. STATEMENT OF SIGNIFICANCE: Enamel microstructure varies significantly with the diversity of diets, bite forces, and tooth shapes exhibited by mammals. However, minimal micromechanical exploration of microstructures outside of humans, leaves our understanding of biomechanical functions in a nascent stage. Using biologically informed mechanical testing, we demonstrate that the complex two-part microstructure that comprises the cutting edge of beaver incisors facilitates self-sharpening of the enamel edge. This previously unrecognized mechanism provides critical maintenance to the shape of the incisal edge ensuring continued functionality despite extreme wear incurred during feeding. More broadly, we show how the architecture of prisms and the surrounding interprismatic matrix dictate the propagation of fractures through enamel fabrics and how the pairing of enamel fabrics can result in biologically advantageous functions.
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Affiliation(s)
- Tyler C Hunt
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA; Mechanical and Physical Properties Laboratory, National High Magnetic Field Laboratory-Florida State University, Tallahassee, FL 32310, USA.
| | - Tomas Grejtak
- Department of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA 18015, USA; Department of Mechanical Engineering, Florida A&M University - Florida State University College of Engineering, Tallahassee, FL 32310, USA; Presently at Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Deeksha Kodangal
- Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011, USA
| | - Soumya Varma
- Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011, USA
| | - Caroline E Rinaldi
- Department of Surgery, University of Texas-Southwestern Medical Center, Dallas, TX 75390, USA
| | - Siddhartha Pathak
- Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011, USA
| | - Brandon A Krick
- Department of Mechanical Engineering, Florida A&M University - Florida State University College of Engineering, Tallahassee, FL 32310, USA
| | - Gregory M Erickson
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA; Mechanical and Physical Properties Laboratory, National High Magnetic Field Laboratory-Florida State University, Tallahassee, FL 32310, USA
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Okayama Y, Hunt TC, Kassel O, Ashman LK, Church MK. Assessment of the anti-c-kit monoclonal antibody YB5.B8 in affinity magnetic enrichment of human lung mast cells. J Immunol Methods 1994; 169:153-61. [PMID: 7510757 DOI: 10.1016/0022-1759(94)90259-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The monoclonal antibody, YB5.B8 binds to the second domain of the c-kit proto-oncogene product on human mast cells, a receptor associated with tyrosine kinase activity. This molecule is involved with cell proliferation, maturation and viability as well as cell activation and its natural ligand is stem cell factor (SCF). We have used this antibody coupled to Dynabeads to perform positive affinity enrichment of human lung mast cells. This procedure results in enrichment of mast cells from 2.6 +/- 0.3% to 85.0 +/- 1.6% purity (n = 29) with yields of 41.9 +/- 3.7% (n = 29). As YB5.B8 interacts with the same receptor domain as does SCF, it is important to demonstrate that this procedure does not modify mast cell function. Incubation of mast cells with 1-5000 ng/ml YB5.B8 for 30 min neither induced histamine release nor modulated histamine release induced by anti-IgE. Furthermore, incubation with YB5.B8 did not alter prolonged culture with SCF. Examination of cells enriched using YB5.B8 showed that they had a normal histamine content (3.8 +/- 0.3 pg/cell compared with 3.9 +/- 0.7 pg/cell unpurified, n = 20) and had unchanged behaviour in both histamine secretion and cell survival studies. These studies indicate that YB5.B8 does not influence mast cell function and thus its use in magnetic affinity purification procedures offers a simple and effective method for enriching human mast cell preparations.
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Affiliation(s)
- Y Okayama
- Immunopharmacology Group, Southampton General Hospital, UK
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Hunt TC, Summers JA, Campos MG, Rimmer SJ, Sturton G, Palfai S, Church MK. Monoclonal antibodies specific for guinea pig eosinophil major basic protein: their use in an ELISA, immunocytochemistry and flow cytometry. Clin Exp Allergy 1993; 23:425-34. [PMID: 8334540 DOI: 10.1111/j.1365-2222.1993.tb00349.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Eosinophil major basic protein (MBP), purified from guinea pig eosinophil granules was used to raise five monoclonal antibodies (MoAbs). Their reactivity with MBP was confirmed by immunoblotting and indirect ELISA. Two of the MoAbs were used to develop a sensitive and specific antigen capture (sandwich) ELISA for guinea pig eosinophil MBP which gives an accurate and reproducible standard curve over the range of 10-10,000 ng/ml. The specificity of the ELISA for MBP was confirmed and its suitability for testing biological samples ascertained by measurement of MBP in bronchoalveolar lavage fluid (BALF) and plasma from guinea pigs sensitized and challenged with ovalbumin. The ELISA was also capable of detecting MBP in culture supernatants from purified eosinophil preparations challenged with calcium ionophore in vitro. One of the monoclonals could be used to strongly and specifically stain guinea pig eosinophils in immunocytochemistry, whilst all five could be used to visualize eosinophils in suspension in BALF or peritoneal lavage fluid by flow cytometry. There was no staining of other guinea pig leucocyte types, nor crossreactivity with human eosinophils by immunocytochemistry or flow cytometry.
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Affiliation(s)
- T C Hunt
- Immunopharmacology Group, Southampton General Hospital, U.K
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Bradding P, Feather IH, Howarth PH, Mueller R, Roberts JA, Britten K, Bews JP, Hunt TC, Okayama Y, Heusser CH. Interleukin 4 is localized to and released by human mast cells. J Exp Med 1992; 176:1381-6. [PMID: 1402683 PMCID: PMC2119427 DOI: 10.1084/jem.176.5.1381] [Citation(s) in RCA: 430] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Recent attention has focused on the T helper type 2 (Th2) lymphocyte as a source of interleukin 4 (IL-4) in allergic disease. However, Th2 cells themselves require a pulse of IL-4 to initiate this synthesis. Here we provide immunohistochemical evidence of IL-4 localization to human mast cells of the skin and respiratory tract, and demonstrate that immunoglobulin E-dependent stimulation of purified human lung mast cells leads to the rapid release of IL-4 into the extracellular environment. We propose that mast cell activation in an allergic response provides a rapid and local pulse of IL-4 into the local environment essential for the triggering of T lymphocytes into sustained IL-4 production and to initiate inflammatory cell accumulation and activation.
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Affiliation(s)
- P Bradding
- Immunopharmacology Group, Medicine I, Southampton General Hospital, United Kingdom
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Rimmer SJ, Akerman CL, Hunt TC, Church MK, Holgate ST, Shute JK. Density profile of bronchoalveolar lavage eosinophils in the guinea pig model of allergen-induced late-phase allergic responses. Am J Respir Cell Mol Biol 1992; 6:340-8. [PMID: 1540398 DOI: 10.1165/ajrcmb/6.3.340] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Inhalation of aerosolized ovalbumin by guinea pigs both during sensitization and upon challenge induces a pulmonary eosinophilia as assessed by cells recovered in bronchoalveolar lavage fluid (BALF). In comparison with BALF eosinophil numbers in naive animals of 0.82 +/- 0.2 x 10(6) cells, those in sensitized animals before challenge and 17 and 72 h after challenge were 1.48 +/- 0.2 x 10(6), 2.60 +/- 0.6 x 10(6), and 4.2 +/- 0.7 x 10(6) cells, respectively. BALF eosinophils from all these groups were notable for their heterogeneity with respect to density, size, and appearance under the electron microscope. In comparison with peritoneal eosinophils, which had a single mean density peak of 1.088 +/- 0.001 g/ml, BALF cells comprised hypodense (less than 1.080 g/ml), normodense (1.080 to 1.096 g/ml), and hyperdense (greater than 1.096 g/ml) eosinophils. The percentage of hypodense eosinophils rose from 25% in naive animals to 63% in sensitized animals (P less than 0.001) and fell after challenge. In contrast, challenge induced the appearance of hyperdense eosinophils, which rose from 6% in sensitized animals to 42% 72 h after challenge (P less than 0.001). Blood eosinophils in naive animals showed a similar profile to those in the lung, but after sensitization and challenge no gross changes in the proportion of either hypodense or hyperdense eosinophils were observed. Flow cytometric analysis of BALF eosinophils indicated that hypodense eosinophils, with a mean diameter of 15.8 microns, were larger than both normodense and hyperdense eosinophils, which had mean diameters of 14.3 and 11.6 microns, respectively. Although the numbers and size of granules were not reduced in hypodense BAL eosinophils, electron microscopy morphology indicated a reduced granular content.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S J Rimmer
- Immunopharmacology Group, Southampton General Hospital, United Kingdom
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Hunt TC, Campbell AM, Robinson C, Holgate ST. Structural and secretory characteristics of bovine lung and skin mast cells: evidence for the existence of heterogeneity. Clin Exp Allergy 1991; 21:173-82. [PMID: 1710530 DOI: 10.1111/j.1365-2222.1991.tb00827.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We have examined cells dispersed enzymatically from three different sites in the bovine lung (tracheal mucosa, bronchial mucosa and parenchyma) and the skin, in order to ascertain whether the bovine model could be used to study mast cell heterogeneity. Histochemically there were two sub-populations of mast cells present in both lung and skin (on the basis of toluidine blue staining and the sensitivity to formalin fixation), but their proportions were similar in all sites studied. Skin mast cells contained approximately twice the amount of histamine than their counterparts in the lung (P less than 0.05). Functional heterogeneity was examined by in vitro release of histamine following secretagogue challenge. Calcium ionophore induced a substantial release of histamine; skin mast cells releasing significantly more histamine than any of the lung mast cells (at 10 microM ionophore, 37.1% and 20.7% net histamine release, respectively, P less than 0.05), although the time-course of release from the two tissues was similar. The neuropeptides vasoactive intestinal peptide and somatostatin induced a modest but statistically significant release of histamine from both skin and lung mast cells, whilst substance P only induced histamine secretion from skin mast cells. A range of other potential immunological and non-immunological secretagogues was unsuccessful in eliciting histamine release from mast cells in any of the tissues. We conclude that there were no convincing histochemical differences between mast cells from the sites examined in the lung or skin. Additionally, there was no discernable functional heterogeneity between mast cells within the lung, but functional differences were evident between mast cells of the bovine lung and skin. However, in the absence of a suitable immunological stimulus the bovine model cannot be regarded as a good model of mast cell heterogeneity.
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Affiliation(s)
- T C Hunt
- Immunopharmacology Group, Southampton General Hospital, U.K
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Hunt TC, Rowley AF. Leukotriene B4 induces enhanced migration of fish leucocytes in vitro. Immunol Suppl 1986; 59:563-8. [PMID: 3026961 PMCID: PMC1453334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Leukotriene B4 (LTB4) was found to induce enhanced migration of the eosinophilic G1 granulocyte of the dogfish Scyliorhinus canicula in the migration under agarose assay. Higher levels of LTB4, however, were required to produce this effect than with mammalian neutrophils under similar conditions. It is postulated that this may be due to the dogfish granulocytes possessing fewer receptors for LTB4 than their mammalian counterparts. The eosinophilic G3 granulocyte was also tested using the same assay but results were inconclusive. The effect of LTB4 on dogfish G1 and G3 granulocytes was also monitored with the bipolar shape formation (BSF) assay. LTB4 induced BSF in both granulocyte types, and this method appeared to be more sensitive than the migration under agarose assay. Whether the enhanced migration observed is a result of chemotaxis or chemokinesis is not determined. This present study represents the first known report of the function of LTB4 in a non-mammalian vertebrate.
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Hunt TC, Rowley AF. Preliminary studies on the chemotactic potential of dogfish (Scyliorhinus canicula) leucocytes using the bipolar shape formation assay. Vet Immunol Immunopathol 1986; 12:75-82. [PMID: 3765365 DOI: 10.1016/0165-2427(86)90112-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The bipolar shape formation assay, previously used to determine the chemotactic potential of various factors for mammalian leucocytes, was tested in the present study with granulocytes of the lesser spotted dogfish, Scyliorhinus canicula. Bipolar shape formation was found to be a temperature dependent process with maximal formation observed at 30 degrees C. Addition of the formyl peptide, N-formyl-methionyl-phenylalanine failed to induce any bipolar forms at all temperatures and concentrations tested.
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Hunt TC. General aims of the tests of the Temporary Registration Assessment Board. Proc R Soc Med 1976; 69:812-3. [PMID: 1005462 PMCID: PMC1864725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Hunt TC. Assessment for Temporary Registration [ Abridged]. Proc R Soc Med 1976. [DOI: 10.1177/003591577606901112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Abstract
1. After oral administration of [14C]carbenoxolone (100 mg, 5 μCi) to patients with radiologically-proven gastric ulcers the radioactivity was excreted mostly in the faeces (70–80%) with lesser amounts in the expired CO2 (12–20%) and only traces in the urine (0·2–1%). This is in marked contrast with the metabolism and pattern of excretion of this drug in the rat.
2. Most of the radioactivity excreted in the faeces of patients was present as carbenoxolone, which was probably formed by bacterial hydrolysis of the biliary-excreted conjugate of carbenoxolone.
3. It is concluded that in man orally administered carbenoxolone is absorbed mostly unchanged, in contrast with the rat in which the orally administered drug is substantially hydrolysed to β-glycyrrhetic acid and succinic acid before absorption.
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Hunt TC. Colonic irrigation. Practitioner 1972; 208:523-4. [PMID: 5031041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Tancock S, Hunt TC. Fallot's tetralogy: a case study. Nurs Times 1968; 64:1303-5. [PMID: 4175684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Hunt TC. Splenomegaly with Anaemia. Proc R Soc Med 1933; 26:370. [PMID: 19989130 PMCID: PMC2204516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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Hunt TC. Polycythaemia Vera. Proc R Soc Med 1933; 26:364. [PMID: 19989124 PMCID: PMC2204553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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Hunt TC. Splenomegaly with Anæmia. Proc R Soc Med 1933; 26:370. [PMID: 20913527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
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Hunt TC. Polycythæmia Vera. Proc R Soc Med 1933; 26:364. [PMID: 20913521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
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