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Journal articles on the topic 'TetraNuc'

Author: Grafiati
Published: 4 June 2021
Last updated: 1 February 2022

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1

DUDEK, J., D. CURIEN, A. GÓŹDŹ, and K. MAZUREK. "NUCLEAR POINT-GROUP SYMMETRIES AND NEW IDEAS ABOUT NUCLEAR STABILITY: AN OVERVIEW." International Journal of Modern Physics E 18, no. 10 (November 2009): 2155–59. http://dx.doi.org/10.1142/s0218301309014470.

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The nuclear mean-field theory and the group representation theory can be used to optimise the search for strong nuclear shell effects. The two theories allow to correlate the symmetry aspects with the presence of large gaps in the single-particle spectra, facilitate in this way the conditions of search for strong nucleonic- and nuclear-binding and thus for an increased nuclear stability. In this article we give a short overview of the related on-going research, focussing on the results of the TetraNuc Collaboration.
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2

CURIEN, D., J. DUDEK, H. MOLIQUE, L. SENGELE, A. GÓŹDŹ, and K. MAZUREK. "SEARCH FOR TETRAHEDRAL SYMMETRY IN NUCLEI: A SHORT OVERVIEW." International Journal of Modern Physics E 20, no. 02 (February 2011): 219–27. http://dx.doi.org/10.1142/s0218301311017557.

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Following a series of experiments launched by the TetraNuc collaboration to possibly demonstrate the existence of high-rank symmetries in subatomic physics, the first experimental results on the Rare Earth region appear in publications. Meanwhile an important progress has been made on the theory side strongly suggesting that the original criterion of the static tetrahedral symmetry in the form of vanishing quadrupole moments may need to be revised to include explicitly the vibrational motion. The Actinide region seems of particular interest because of the extra stability provided by the octahedral symmetry. In this article a summary of the current experimental efforts on both the Rare-Earth and Actinide regions is given. Finally the ELMA project addressing the experimental search for the symmetries in the Actinides is briefly discussed.
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3

Dudek, J., I. Dedes, J. Yang, A. Baran, D. Curien, A. Gaamouci, A. Góźdź, A. Pędrak, and H. L. Wang. "Nuclear High-rank Symmetries: From the Early Theory Predictions via TetraNuc Collaboration to the Final Experimental Discovery." Acta Physica Polonica B Proceedings Supplement 13, no. 3 (2020): 419. http://dx.doi.org/10.5506/aphyspolbsupp.13.419.

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4

Jiang, Minghua, Senhua Chen, Jing Li, and Lan Liu. "The Biological and Chemical Diversity of Tetramic Acid Compounds from Marine-Derived Microorganisms." Marine Drugs 18, no. 2 (February 15, 2020): 114. http://dx.doi.org/10.3390/md18020114.

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Tetramic acid (pyrrolidine-2,4-dione) compounds, isolated from a variety of marine and terrestrial organisms, have attracted considerable attention for their diverse, challenging structural complexity and promising bioactivities. In the past decade, marine-derived microorganisms have become great repositories of novel tetramic acids. Here, we discuss the biological activities of 277 tetramic acids of eight classifications (simple 3-acyl tetramic acids, 3-oligoenoyltetramic acids, 3-decalinoyltetramic acid, 3-spirotetramic acids, macrocyclic tetramic acids, N-acylated tetramic acids, α-cyclopiazonic acid-type tetramic acids, and other tetramic acids) from marine-derived microbes, including fungi, actinobacteria, bacteria, and cyanobacteria, as reported in 195 research studies up to 2019.
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5

Nagata, Nanae, Sakura Masuko, Rikako Inoue, Tatsuro Nakamura, Kosuke Aritake, and Takahisa Murata. "Development of Monoclonal Antibody-Based EIA for Tetranor-PGDM which Reflects PGD2 Production in the Body." Journal of Immunology Research 2021 (April 26, 2021): 1–6. http://dx.doi.org/10.1155/2021/5591115.

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Tetranor-PGDM is a metabolite of PGD2. Urinary tetranor-PGDM levels were reported to be increased in some diseases, including food allergy, Duchenne muscular dystrophy, and aspirin-intolerant asthma. In this study, we developed a monoclonal antibody (MAb) and a competitive enzyme immunoassay (EIA) for measuring tetranor-PGDM. Spleen cells isolated from mice immunized with tetranor-PGDM were utilized to generate Ab-producing hybridomas. We chose hybridomas and purified MAb against tetranor-PGDM to develop competitive EIA. The assay evaluated the optimal ionic strength, pH, precision, and reliability. Specificity was determined by cross-reactivity to tetranor-PGEM, tetranor-PGFM, and tetranor-PGAM. Recovery was determined by spiking experiments on artificial urine. Optimal ionic strength was 150 mM NaCl, and optimal pH was pH 7.5. Metabolites other than tetranor-PGDM did not show any significant cross-reactivity in the EIA. The assay exhibited a half-maximal inhibition concentration (IC50) of 1.79 ng/mL, limit of detection (LOD) of 0.0498 ng/mL, and range of quantitation (ROQ) value of 0.252 to 20.2 ng/mL. The intra- and inter-assay variation for tetranor-PGDM was 3.9–6.0% and 5.7–10.4%, respectively. The linearity-dilution effect showed excellent linearity under dilution when artificial urine samples were applied to solid-phase extraction (SPE). After SPE, recovery of tetranor-PGDM in artificial urine averaged from 82.3% to 113.5% and was within acceptable limits (80%–120%). We successfully generated one monoclonal antibody and developed a sensitive competitive EIA. The established EIA would be useful for routine detection and monitoring of tetranor-PGDM in research or diagnostic body fluids.
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6

Ueda, Chihiro, Kazuhiro Tateda, Manabu Horikawa, Soichiro Kimura, Yoshikazu Ishii, Kaoru Nomura, Kanako Yamada, et al. "Anti-Clostridium difficile Potential of Tetramic Acid Derivatives from Pseudomonas aeruginosa Quorum-Sensing Autoinducers." Antimicrobial Agents and Chemotherapy 54, no. 2 (November 16, 2009): 683–88. http://dx.doi.org/10.1128/aac.00702-09.

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ABSTRACT We have examined the potential bactericidal activities of several tetramic acids derived from Pseudomonas autoinducers against Clostridium difficile, a cause of antibiotic-associated pseudomembranous colitis. Clinical isolates of C. difficile (n = 4) were incubated in broth with a chemically synthesized Pseudomonas autoinducer and its tetramic acid derivatives. The structure-activity relationship and the mechanisms of action were examined by a time-killing assay and by determination of the morphological/staining characteristics. The use of some tetramic acids derived from N-3-oxododecanoyl l-homoserine lactone resulted in more than 3-log reductions in the viability of C. difficile within 30 min at 30 μM. The outer membrane was suggested to be one of the targets for the bactericidal activity of tetramic acid, because disturbance of the bacterial outer surface was demonstrated by alteration of the Gram-staining characteristic and electron microscopy. The data for the tetramic acid derivatives demonstrate that the keto-enol structure and the length of the acyl side chain of tetramic acid may be essential for the antibacterial activity of this molecule. These results suggest the potential for tetramic acid derivatives to be novel agents with activity against C. difficile.
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7

Neumann, Kerstin, Stefan Kehraus, Michael Gütschow, and Gabriele M. König. "Cytotoxic and HLE-Inhibitory Tetramic Acid Derivatives from Marine-Derived Fungi." Natural Product Communications 4, no. 3 (March 2009): 1934578X0900400. http://dx.doi.org/10.1177/1934578x0900400308.

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Tetramic acid derivatives are an important class of nitrogen heterocycles with a pyrrolidine-2,4-dione core as a key structural motif. From the sponge-derived fungus Beauveria bassiana, a new equisetin-like tetramic acid derivative, beauversetin (1), was isolated. The sea weed-derived fungus Microdiplodia sp. produced the tetramic acid derivative 2 (Sch210972) which was shown to inhibit human leucocyte elastase (HLE) with an IC50 of 1.04 μg mL−1.
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8

Li, Yong, Zheng Huang, Jia Xu, Yong Ding, Dian-Yong Tang, Jie Lei, Hong-yu Li, Zhong-Zhu Chen, and Zhi-Gang Xu. "Microwave-assisted efficient and facile synthesis of tetramic acid derivatives via a one-pot post-Ugi cascade reaction." Beilstein Journal of Organic Chemistry 16 (April 9, 2020): 663–69. http://dx.doi.org/10.3762/bjoc.16.63.

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A facile microwave-assisted method for the synthesis of tetramic acid derivatives has been developed through an Ugi/Dieckmann cyclization strategy with DBU. This two-step one-pot procedure afforded the targeted tetramic acid analogues in good yields. With commercially available Ugi starting materials, microwave irradiation, a simple operation, excellent yields, and a broad scope, this reaction has the potential to produce a large number of tetramic acid analogues, which cannot be easily accessed by the classic synthetic methods.
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9

Yalcin, M., E. Dyskin, L. Lansing, D. J. Bharali, S. S. Mousa, A. Bridoux, A. H. Hercbergs, et al. "Tetraiodothyroacetic Acid (Tetrac) and Nanoparticulate Tetrac Arrest Growth of Medullary Carcinoma of the Thyroid." Journal of Clinical Endocrinology & Metabolism 95, no. 4 (April 1, 2010): 1972–80. http://dx.doi.org/10.1210/jc.2009-1926.

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Abstract Context: Tetraiodothyroacetic acid (tetrac) blocks angiogenic and tumor cell proliferation actions of thyroid hormone initiated at the cell surface hormone receptor on integrin αvβ3. Tetrac also inhibits angiogenesis initiated by vascular endothelial growth factor and basic fibroblast growth factor. Objective: We tested antiangiogenic and antiproliferative efficacy of tetrac and tetrac nanoparticles (tetrac NP) against human medullary thyroid carcinoma (h-MTC) implants in the chick chorioallantoic membrane (CAM) and h-MTC xenografts in the nude mouse. Design: h-MTC cells were implanted in the CAM model (n = 8 per group); effects of tetrac and tetrac NP at 1 μg/CAM were determined on tumor angiogenesis and tumor growth after 8 d. h-MTC cells were also implanted sc in nude mice (n = 6 animals per group), and actions on established tumor growth of unmodified tetrac and tetrac NP ip were determined. Results: In the CAM, tetrac and tetrac NP inhibited tumor growth and tumor-associated angiogenesis. In the nude mouse xenograft model, established 450–500 mm3 h-MTC tumors were reduced in size over 21 d by both tetrac formulations to less than the initial cell mass (100 mm3). Tumor tissue hemoglobin content of xenografts decreased by 66% over the course of administration of each drug. RNA microarray and quantitative real-time PCR of tumor cell mRNAs revealed that both tetrac formulations significantly induced antiangiogenic thrombospondin 1 and apoptosis activator gene expression. Conclusions: Acting via a cell surface receptor, tetrac and tetrac NP inhibit growth of h-MTC cells and associated angiogenesis in CAM and mouse xenograft models.
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10

Achilli, Silvia, João T. Monteiro, Sonia Serna, Sabine Mayer-Lambertz, Michel Thépaut, Aline Le Roy, Christine Ebel, et al. "TETRALEC, Artificial Tetrameric Lectins: A Tool to Screen Ligand and Pathogen Interactions." International Journal of Molecular Sciences 21, no. 15 (July 25, 2020): 5290. http://dx.doi.org/10.3390/ijms21155290.

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C-type lectin receptor (CLR)/carbohydrate recognition occurs through low affinity interactions. Nature compensates that weakness by multivalent display of the lectin carbohydrate recognition domain (CRD) at the cell surface. Mimicking these low affinity interactions in vitro is essential to better understand CLR/glycan interactions. Here, we present a strategy to create a generic construct with a tetrameric presentation of the CRD for any CLR, termed TETRALEC. We applied our strategy to a naturally occurring tetrameric CRD, DC-SIGNR, and compared the TETRALEC ligand binding capacity by synthetic N- and O-glycans microarray using three different DC-SIGNR constructs i) its natural tetrameric counterpart, ii) the monomeric CRD and iii) a dimeric Fc-CRD fusion. DC-SIGNR TETRALEC construct showed a similar binding profile to that of its natural tetrameric counterpart. However, differences observed in recognition of low affinity ligands underlined the importance of the CRD spatial arrangement. Moreover, we further extended the applications of DC-SIGNR TETRALEC to evaluate CLR/pathogens interactions. This construct was able to recognize heat-killed Candida albicans by flow cytometry and confocal microscopy, a so far unreported specificity of DC-SIGNR. In summary, the newly developed DC-SIGNR TETRALEC tool proved to be useful to unravel novel CLR/glycan interactions, an approach which could be applied to other CLRs.
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11

Kafka, Zdeněk, and Luděk Vodička. "Isomerization of binor S." Collection of Czechoslovak Chemical Communications 50, no. 5 (1985): 1212–15. http://dx.doi.org/10.1135/cccc19851212.

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The isomerization of norbornadiene dimer, heptacyclo[8,4,0,02,12, 03,8,04,6,05,9,011,13]tetradecane (binor S), was studied in the presence of various catalysts. The isomerization resulted in a mixture of hexacyclic olefins (hexacyclo[8,4,0,02,7,03,14,04,8,09,13]tetradec-5-ene and hexacyclo[6,6,0,02,6,05,14,07,12,09,13]tetradec-3-ene), which is an important intermediate product in the five-stage synthesis of triamantane.
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12

Kafka, Zdeněk, and Luděk Vodička. "The Diels-Alder reaction of butadiene with hexacyclic olefins in the synthesis of triamantane." Collection of Czechoslovak Chemical Communications 51, no. 5 (1986): 1083–85. http://dx.doi.org/10.1135/cccc19861083.

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The paper describes the composition of products arising from the Diels-Alder reaction of butadiene with hexacyclic olefins (hexacyclo[8,4,0,02,7,03,14,04,8,09,13]tetradec-5-ene and hexacyclo[6,6,0,02,6,05,14,07,12,09,13]tetradec-3-ene) under different conditions. The reaction afforded a mixture of heptacyclic olefins (heptacyclo[8,8,0,02,17,03,11,04,9,012,16,013,18]octadec-6-ene and heptacyclo[8,8,0,02,13,03,11,04,9,012,17,014,18]octadec-6-ene), which is an important intermediate in the synthesis of triamantane.
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13

Mousa, Shaker A., Laura O’Connor, Ahmad Aljada, Paul Davis, and Abdelhadi Rebbaa. "Suppression of Angiogenesis and Resistance to Doxorubicin by the Thyroid Hormone Tetraiodothyroacetic Acid." Blood 110, no. 11 (November 16, 2007): 4209. http://dx.doi.org/10.1182/blood.v110.11.4209.4209.

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Abstract Thyroid hormone has been recently shown to induce tumor growth and angiogenesis. These angiogenesis modulating activities are initiated at endothelial cell plasma membrane receptor via the integrin αVβ3, at or near the Arg-Gly-Asp (RGD) recognition site on the integrin. In the present study, we have investigated the effect of tetraiodothyroacetic acid (tetrac), a deaminated thyroid hormone analog that inhibits thyroid hormone-binding to the cell surface integrin, on angiogenesis and cancer cell resistance to doxorubicin both in vitro and in vivo. Two angiogenesis models were studied in which vascular endothelial growth factor, VEGF165 or basic fibroblast growth factor, FGF2 (1–2 μg/ml) or thyroid hormone, thyroxin (L-T4 or T3) were used either to induce tube formation in the human dermal micro-vascular endothelial cells (HDMEC), or to stimulate new blood vessel branch formation in the chick chorioallantoic membrane (CAM) models. In both models, Tetrac (0.1–10 μM) inhibited the pro-angiogenesis activity of VEGF, FGF2, L-T4 or T3 by more than 50% at 1.0 uM RT-PCR revealed that tetrac (1–3 μM) decreased abundance of angiopoietin-2 mRNA but did not affect the mRNA levels of angiopoietin-1, in VEGF-exposed endothelial cells, suggesting that specific angiogenic pathways are targeted by this compound. Additionally, microarray was used to examine changes in expression of Matrix Metalloproteinases (MMP) and Tissue Inhibitor of Metalloproteinases (TIMP) following VEGF treatment with and without tetrac. HDMEC cells treated with VEGF exhibited 3–5-fold increase in MMP-15 and MMP-19 expression and tetrac (3μM), inhibited expression of MMP-15 and MMP-19 by 3–9-fold, respectively. Expression of TIMP-3 was increased 5.4-fold following VEGF and tetrac treatment when compared to treatment with VEGF alone. This finding suggests that part of the mechanism by which tetrac inhibits VEGF-stimulated angiogenesis involves inhibition of certain MMPs and increase in TIMP expression. Investigation of the anti-proliferative function of tetrac was carried out using the αVβ3 expressing breast cancer cells MC7 and their drug resistant counterparts. Interestingly, proliferation of both cell lines was inhibited similarly by tetrac suggesting that this analog may circumvent drug resistance. In fact, tetrac was able to reverse resistance to doxorubicin in vitro and to suppress growth of doxorubicin resistant tumors in nude mice. Inhibition of the drug transporter p-glycoprotein was found to play a key role in mediating the action of tetrac. Taken together, findings presented in this study provide evidence that the anticancer function of tetrac can be attributed to its anti-angiogenic and drug resistance reversal activities.
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Stachel, Hans-Dietrich, and Josef Schachtner. "Synthese von Heteroanaloga der Penicillsäure / Synthesis of Hetero Analogues of Penicillic Acid." Zeitschrift für Naturforschung B 51, no. 9 (September 1, 1996): 1334–38. http://dx.doi.org/10.1515/znb-1996-0919.

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Cohen, Keren, Uri Abadi, Aleck Hercbergs, Paul J. Davis, Martin Ellis, and Osnat Ashur-Fabian. "The induction of myeloma cell death and DNA damage by tetrac, a thyroid hormone derivative." Endocrine-Related Cancer 25, no. 1 (January 2018): 21–34. http://dx.doi.org/10.1530/erc-17-0246.

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Multiple myeloma (MM) is a plasma cell malignancy in which involvement of the thyroid hormone-integrin αvβ3 pathway was shown, and pharmacologic inhibition of this pathway is a rational approach to disease management. A thyroid hormone derivative, tetraiodothyroacetic acid (tetrac), which inhibitsl-thyroxine (T4) and 3,5,3′-triiodo-l-thyronine (T3) binding to αvβ3 integrin, was studied in five MM cell lines and primary bone marrow (BM) MM cells. Tetrac inhibited MM cell proliferation (absolute cell number/viability) and induced caspase-dependent apoptosis (annexin-V/PI and cell cycle). Activation of caspase-9 and caspase-3 was further demonstrated. Moreover, DNA damage markers, ataxia-telangiectasia-mutated (ATM) kinase, poly ADP-ribose polymerase (PARP-1) and histone γH2AX were induced by tetrac. The various tetrac-initiated effects were attenuated by Arg-Gly-Asp (RGD) peptide, suggesting integrin involvement. Primary BM mononuclear cells were harvested from MM patients (n = 39) at various disease stages. Tetrac-induced apoptosis (12/17 samples) and sensitized the cytotoxic action of bortezomib (6/9 samples). Lastly, expression of plasma membrane integrin αvβ3 was shown not only in the malignant plasma clone, but also in other cell populations within the BM samples (n = 25). Tetrac is anti-proliferative and pro-apoptotic in MM and cells may offer a therapeutic approach for this disease.
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Matiadis, Dimitris. "Metal-Catalyzed and Metal-Mediated Approaches to the Synthesis and Functionalization of Tetramic Acids." Catalysts 9, no. 1 (January 7, 2019): 50. http://dx.doi.org/10.3390/catal9010050.

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The heterocyclic ring of tetramic acids is found in naturally occurred biologically active products isolated from fungi, bacteria, molds, and sponges. Thus, these molecules have attracted significant attention as synthetic targets, and various synthetic paths have been developed. Over recent years, a growing number of catalytic approaches toward functionalized products have been established in order to overcome the limitations of the conventional methods. The present review describes the strategies for the metal-catalyzed and metal-promoted synthesis and further derivatization of tetramic acids, with emphasis on recent examples from the literature.
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Grunwald, Alyssa L., Fabrice Berrué, David P. Overy, and Russell G. Kerr. "Isolation of iqalisetins A and B from a Tolypocladium sp. isolated from marine sediment from Frobisher Bay in Canada’s arctic." Canadian Journal of Chemistry 94, no. 4 (April 2016): 444–48. http://dx.doi.org/10.1139/cjc-2015-0439.

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Two new decalin-tetramic acid compounds, iqalisetin A (1) and iqalisetin B (2), were identified from a Tolypocladium sp. isolated from a marine sediment sample collected from Frobisher Bay, Nunavut, in Canada’s arctic. The structures of the new compounds were elucidated by NMR experiments. The relative stereochemistry of the decalin skeleton was determined by NOESY experiments and confirmed that 1 and 2 contained a trans-decalin ring system. The absolute stereochemistry of the tetramic acid was determined using Marfey’s method. Compounds 1 and 2 did not exhibit any significant antimicrobial or cytotoxic activity.
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Corwin, D. L., and B. L. Waggoner. "TETrans: A User-Friendly, Functional Model of Solute Transport." Water Science and Technology 24, no. 6 (September 1, 1991): 57–65. http://dx.doi.org/10.2166/wst.1991.0141.

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A beta-test version of TETrans (acronym for Trace Element Transport) is presented which models the movement of inorganic solutes through the vadose zone under transient-state conditions. TETrans is a complete software package consisting of an interactive tutorial, user's guide and applications software. Both IBM-compatible and Macintosh versions are available to users. TETrans is specifically designed to be intuitive in its operation and require only readily available input parameters in order to enhance its utility as a real-world applications tool for transport modeling. The transport model utilizes a mass-balance approach to determine solute concentration distributions over time and solute-loading to the groundwater. Several modeling options are available for simulating such transport-influencing factors as plant-water uptake, hydraulic bypass and adsorption. In the Macintosh version, TETrans makes full use of the Macintosh interface to enhance the user-friendliness of the model. All functions are available from pull-down menus, and simulation results are displayed in text and graphic windows. Test data are shown which include a comparison of simulated and measured results for the movement of chloride through a soil lysimeter column over a 900-day study period. Excellent agreement is found when a single parameter for bypass is used. TETrans is distinguished from other transport models in the straightforward manner in which it handles the exacerbating problem of hydraulic bypass. The hydraulic bypass parameter, termed the mobility coefficient, is determined from simple chemical analysis of chloride in the soil solution through the soil profile following the application of a plug of chloride in the irrigation water. The mobility coefficient reflects the volume of soil water which is not subject to piston displacement
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Huang, Chi-Hung, Tung-Yung Huang, Wong-Jin Chang, Yi-shin Pan, Hung-Ru Chu, Zi-Lin Li, Sukanya Unson, et al. "Combined Treatment of Heteronemin and Tetrac Induces Antiproliferation in Oral Cancer Cells." Marine Drugs 18, no. 7 (July 2, 2020): 348. http://dx.doi.org/10.3390/md18070348.

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Background: Heteronemin, a marine sesterterpenoid-type natural product, possesses an antiproliferative effect in cancer cells. In addition, heteronemin has been shown to inhibit p53 expression. Our laboratory has demonstrated that the thyroid hormone deaminated analogue, tetrac, activates p53 and induces antiproliferation in colorectal cancer. However, such drug mechanisms are still to be studied in oral cancer cells. Methods: We investigated the antiproliferative effects by Cell Counting Kit-8 and flow cytometry. The signal transduction pathway was measured by Western blotting analyses. Quantitative PCR was used to evaluate gene expression regulated by heteronemin, 3,3’,5,5’-tetraiodothyroacetic acid (tetrac), or their combined treatment in oral cancer cells. Results: Heteronemin inhibited not only expression of proliferative genes and Homo Sapiens Thrombospondin 1 (THBS-1) but also cell proliferation in both OEC-M1 and SCC-25 cells. Remarkably, heteronemin increased TGF-β1 expression in SCC-25 cells. Tetrac suppressed expression of THBS-1 but not p53 expression in both cancer cell lines. Furthermore, the synergistic effect of tetrac and heteronemin inhibited ERK1/2 activation and heteronemin also blocked STAT3 signaling. Combined treatment increased p53 protein and p53 activation accumulation although heteronemin inhibited p53 expression in both cancer cell lines. The combined treatment induced antiproliferation synergistically more than a single agent. Conclusions: Both heteronemin and tetrac inhibited ERK1/2 activation and increased p53 phosphorylation. They also inhibited THBS-1 expression. Moreover, tetrac suppressed TGF-β expression combined with heteronemin to further enhance antiproliferation and anti-metastasis in oral cancer cells.
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Myrtle, J. D., A. M. Beekman, and R. A. Barrow. "Ravynic acid, an antibiotic polyeneyne tetramic acid from Penicillium sp. elucidated through synthesis." Organic & Biomolecular Chemistry 14, no. 35 (2016): 8253–60. http://dx.doi.org/10.1039/c6ob00938g.

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Horn, Sigrun, Simone Kersseboom, Steffen Mayerl, Julia Müller, Claudia Groba, Marija Trajkovic-Arsic, Tobias Ackermann, Theo J. Visser, and Heike Heuer. "Tetrac Can Replace Thyroid Hormone During Brain Development in Mouse Mutants Deficient in the Thyroid Hormone Transporter Mct8." Endocrinology 154, no. 2 (January 10, 2013): 968–79. http://dx.doi.org/10.1210/en.2012-1628.

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The monocarboxylate transporter 8 (MCT8) plays a critical role in mediating the uptake of thyroid hormones (THs) into the brain. In patients, inactivating mutations in the MCT8 gene are associated with a severe form of psychomotor retardation and abnormal serum TH levels. Here, we evaluate the therapeutic potential of the TH analog 3,5,3′,5′-tetraiodothyroacetic acid (tetrac) as a replacement for T4 in brain development. Using COS1 cells transfected with TH transporter and deiodinase constructs, we could show that tetrac, albeit not being transported by MCT8, can be metabolized to the TH receptor active compound 3,3′,5-triiodothyroacetic acid (triac) by type 2 deiodinase and inactivated by type 3 deiodinase. Triac in turn is capable of replacing T3 in primary murine cerebellar cultures where it potently stimulates Purkinje cell development. In vivo effects of tetrac were assessed in congenital hypothyroid Pax8-knockout (KO) and Mct8/Pax8 double-KO mice as well as in Mct8-KO and wild-type animals after daily injection of tetrac (400 ng/g body weight) during the first postnatal weeks. This treatment was sufficient to promote TH-dependent neuronal differentiation in the cerebellum, cerebral cortex, and striatum but was ineffective in suppressing hypothalamic TRH expression. In contrast, TSH transcript levels in the pituitary were strongly down-regulated in response to tetrac. Based on our findings we propose that tetrac administration offers the opportunity to provide neurons during the postnatal stage with a potent TH receptor agonist, thereby eventually reducing the neurological damage in patients with MCT8 mutations without deteriorating the thyrotoxic situation in peripheral tissues.
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Davis, Paul J., Gennadi V. Glinsky, Hung-Yun Lin, and Shaker A. Mousa. "Actions of Thyroid Hormone Analogues on Chemokines." Journal of Immunology Research 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/3147671.

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The extracellular domain of plasma membrane integrinαvβ3 contains a receptor for thyroid hormone (L-thyroxine, T4; 3,5,3′-triiodo-L-thyronine, T3); this receptor also binds tetraiodothyroacetic acid (tetrac), a derivative of T4. Tetrac inhibits the binding of T4and T3to the integrin. Fractalkine (CX3CL1) is a chemokine relevant to inflammatory processes in the CNS that are microglia-dependent but also important to normal brain development. Expression of the CX3CL1 gene is downregulated by tetrac, suggesting that T4and T3may stimulate fractalkine expression. Independently of its specific receptor (CX3CR1), fractalkine binds toαvβ3 at a site proximal to the thyroid hormone-tetrac receptor and changes the physical state of the integrin. Tetrac also affects expression of the genes for other CNS-relevant chemokines, including CCL20, CCL26, CXCL2, CXCL3, and CXCL10. The chemokine products of these genes are important to vascularity of the brain, particularly of the choroid plexus, to inflammatory processes in the CNS and, in certain cases, to neuroprotection. Thyroid hormones are known to contribute to regulation of each of these CNS functions. We propose that actions of thyroid hormone and hormone analogues on chemokine gene expression contribute to regulation of inflammatory processes in brain and of brain blood vessel formation and maintenance.
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Sparnon, Tony. "Ischiopagus tetrapus conjoined twins." Journal of Pediatric Surgery 22, no. 7 (July 1987): 676. http://dx.doi.org/10.1016/s0022-3468(87)80125-2.

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Somasundaram, K., and K. S. Wong. "Ischiopagus tetrapus conjoined twins." British Journal of Surgery 73, no. 9 (September 1986): 738–41. http://dx.doi.org/10.1002/bjs.1800730920.

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25

Trost, Barry M., Ehesan U. Sharif, and James J. Cregg. "Ru-catalyzed sequence for the synthesis of cyclic amido-ethers." Chemical Science 8, no. 1 (2017): 770–74. http://dx.doi.org/10.1039/c6sc02849g.

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26

Zaghouani, Mehdi, and Bastien Nay. "3-Acylated tetramic and tetronic acids as natural metal binders: myth or reality?" Natural Product Reports 33, no. 4 (2016): 540–48. http://dx.doi.org/10.1039/c5np00144g.

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Loke, Inga, Guillaume Bentzinger, Julia Holz, Aruna Raja, Aman Bhasin, Florenz Sasse, Andreas Köhn, Rainer Schobert, and Sabine Laschat. "Synthesis of the AB ring system of clifednamide utilizing Claisen rearrangement and Diels–Alder reaction as key steps." Organic & Biomolecular Chemistry 14, no. 3 (2016): 884–94. http://dx.doi.org/10.1039/c5ob01491c.

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A synthesis to the functionalized AB ring system of clifednamide, member of macrocyclic tetramic acid lactams, was developed involving an Ireland–Claisen rearrangement and an intramolecular Diels–Alder reaction.
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28

Davis, Paul J., Shaker A. Mousa, and Hung-Yun Lin. "Nongenomic Actions of Thyroid Hormone: The Integrin Component." Physiological Reviews 101, no. 1 (January 1, 2021): 319–52. http://dx.doi.org/10.1152/physrev.00038.2019.

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The extracellular domain of plasma membrane integrin αvβ3 contains a cell surface receptor for thyroid hormone analogues. The receptor is largely expressed and activated in tumor cells and rapidly dividing endothelial cells. The principal ligand for this receptor is l-thyroxine (T4), usually regarded only as a prohormone for 3,5,3′-triiodo-l-thyronine (T3), the hormone analogue that expresses thyroid hormone in the cell nucleus via nuclear receptors that are unrelated structurally to integrin αvβ3. At the integrin receptor for thyroid hormone, T4 regulates cancer and endothelial cell division, tumor cell defense pathways (such as anti-apoptosis), and angiogenesis and supports metastasis, radioresistance, and chemoresistance. The molecular mechanisms involve signal transduction via mitogen-activated protein kinase and phosphatidylinositol 3-kinase, differential expression of multiple genes related to the listed cell processes, and regulation of activities of other cell surface proteins, such as vascular growth factor receptors. Tetraiodothyroacetic acid (tetrac) is derived from T4 and competes with binding of T4 to the integrin. In the absence of T4, tetrac and chemically modified tetrac also have anticancer effects that culminate in altered gene transcription. Tumor xenografts are arrested by unmodified and chemically modified tetrac. The receptor requires further characterization in terms of contributions to nonmalignant cells, such as platelets and phagocytes. The integrin αvβ3 receptor for thyroid hormone offers a large panel of cellular actions that are relevant to cancer biology and that may be regulated by tetrac derivatives.
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29

Shang, Zhuo, Li Li, Breno P. Espósito, Angela A. Salim, Zeinab G. Khalil, Michelle Quezada, Paul V. Bernhardt, and Robert J. Capon. "New PKS-NRPS tetramic acids and pyridinone from an Australian marine-derived fungus, Chaunopycnis sp." Organic & Biomolecular Chemistry 13, no. 28 (2015): 7795–802. http://dx.doi.org/10.1039/c5ob01058f.

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30

Chen, Min, Chun-Wen Geng, Ling Han, Yu Liu, Yong-Kai Yu, Ai-Min Lu, Chun-Long Yang, and Guo-Hua Li. "Design, synthesis, crystal structure, and herbicidal activity of novel pyrrolidine-2,4-dione derivatives incorporating an alkyl ether pharmacophore with natural tetramic acids as lead compounds." New Journal of Chemistry 45, no. 12 (2021): 5621–30. http://dx.doi.org/10.1039/d1nj00119a.

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A series of pyrrolidine-2,4-dione derivatives incorporating a chainlike alkoxyalkyl moiety or substituted phenoxyethyl moiety were designed and synthesized based on natural tetramic acids. Some target compounds showed obvious herbicidal activities.
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31

Liang, Xiao, Zhong-Hui Huang, Xuan Ma, and Shu-Hua Qi. "Unstable Tetramic Acid Derivatives from the Deep-Sea-Derived Fungus Cladosporium sphaerospermum EIODSF 008." Marine Drugs 16, no. 11 (November 15, 2018): 448. http://dx.doi.org/10.3390/md16110448.

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Seven new unstable tetramic acid derivatives, cladosporiumins I-O (1–7), together with the known analogue cladodionen (8) were isolated from the extract of the deep-sea-derived fungus Cladosporium sphaerospermum EIODSF 008. Their structures were elucidated by spectroscopic analysis, quantum chemical calculations and ECD spectra. Compound 4 was a Mg complex of tetramic acid derivative. In acidic solvent, 4 could change to 1 and 6, and 7 could change to 5. In addition, 1, 5 and 8 existed as two exchangeable isomers, respectively. The structures of cladosporiumins E-H were reassigned as their Na complexes. The antibacterial and cytotoxic activities of 1–8 were also evaluated. However, because of their instability, all of the isolated compounds did not show significant antibacterial activity as the preliminary EtOAc extracts of the fungal strain.
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Matiadis, Dimitrios, Dimitrios Tsironis, Valentina Stefanou, Olga Igglessi–Markopoulou, Vickie McKee, Yiannis Sanakis, Katerina N. Lazarou, Athanassios Chrissanthopoulos, Spyros N. Yannopoulos, and John M. Markopoulos. "X-Ray Crystallographic Analysis, EPR Studies, and Computational Calculations of a Cu(II) Tetramic Acid Complex." Bioinorganic Chemistry and Applications 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/7895023.

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In this work we present a structural and spectroscopic analysis of a copper(II) N-acetyl-5-arylidene tetramic acid by using both experimental and computational techniques. The crystal structure of the Cu(II) complex was determined by single crystal X-ray diffraction and shows that the copper ion lies on a centre of symmetry, with each ligand ion coordinated to two copper ions, forming a 2D sheet. Moreover, the EPR spectroscopic properties of the Cu(II) tetramic acid complex were also explored and discussed. Finally, a computational approach was performed in order to obtain a detailed and precise insight of product structures and properties. It is hoped that this study can enrich the field of functional supramolecular systems, giving place to the formation of coordination-driven self-assembly architectures.
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Schmohl, Kathrin A., Yang Han, Mariella Tutter, Nathalie Schwenk, Rim S. J. Sarker, Katja Steiger, Sibylle I. Ziegler, Peter Bartenstein, Peter J. Nelson, and Christine Spitzweg. "Integrin αvβ3-dependent thyroid hormone effects on tumour proliferation and vascularisation." Endocrine-Related Cancer 27, no. 12 (December 2020): 685–97. http://dx.doi.org/10.1530/erc-20-0353.

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Thyroid hormones are emerging as critical regulators of tumour growth and progression. To assess the contribution of thyroid hormone signalling via integrin αvβ3, expressed on many tumour cells, endothelial cells, and stromal cells, to tumour growth, we compared the effects of thyroid hormones vs tetrac, a specific inhibitor of thyroid hormone action at integrin αvβ3, in two murine xenograft tumour models with and without integrin αvβ3 expression. Integrin αvβ3-positive human anaplastic thyroid cancer cells SW1736 and integrin αvβ3-negative human hepatocellular carcinoma cells HuH7 were injected into the flanks of nude mice. Tumour growth was monitored in euthyroid, hyperthyroid, hypothyroid, and euthyroid tetrac-treated mice. In SW1736 xenografts, hyperthyroidism led to a significantly increased tumour growth resulting in a decreased survival compared to euthyroid mice, while tumour growth was significantly reduced and, hence, survival prolonged in hypothyroid and tetrac-treated mice. Both proliferation and vascularisation, as determined by Ki67 and CD31 immunofluorescence staining, respectively, were significantly increased in tumours from hyperthyroid mice as compared to hypothyroid and tetrac-treated mice. No differences in tumour growth, survival, or Ki67 staining were observed between the different groups in integrin αvβ3-negative HuH7 xenografts. Vascularisation, however, was significantly decreased in hypothyroid and tetrac-treated mice compared to euthyroid and hyperthyroid mice. Apoptosis was not affected in either tumour model, nor were cell proliferation or apoptosis in vitro. Tumour growth regulation by thyroid hormones in αvβ3-positive tumours has important implications for cancer patients, especially those with thyroid dysfunctions and thyroid cancer patients treated with thyrotropin-suppressive L-thyroxine doses.
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Josa-Culleré, Laia, Kirsten E. Christensen, and Mark G. Moloney. "Diastereoselective reduction of the tricarbonyl moiety in bicyclic tetramates giving pyroglutamates." Organic & Biomolecular Chemistry 16, no. 15 (2018): 2705–10. http://dx.doi.org/10.1039/c8ob00187a.

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The formation of densely functionalised bicyclic tetramic acids by both stereoselective reduction and Grignard displacement of a Weinreb amide gives bioactive small molecules, with antibacterial activity along with some cancer-cell line inhibitory activity.
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Mo, Xuhua, Qinglian Li, and Jianhua Ju. "Naturally occurring tetramic acid products: isolation, structure elucidation and biological activity." RSC Adv. 4, no. 92 (2014): 50566–93. http://dx.doi.org/10.1039/c4ra09047k.

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Natural products containing the tetramic acid core scaffold have been isolated from an assortment of terrestrial and marine species and often display wide ranging and potent biological activities including antibacterial, antiviral and antitumoral activities.
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36

Godugu, Kavitha, Hung-yun Lin, Shaker A. Mousa, and Paul J. Davis. "Chemically-Modified Tetraiodothyroacetic Acid (Tetrac) Induces Cancer Cell Apoptosis and Facilitates Clearance of Apoptotic Debris (Efferocytosis)." Journal of the Endocrine Society 5, Supplement_1 (May 1, 2021): A1012—A1013. http://dx.doi.org/10.1210/jendso/bvab048.2071.

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Abstract Tetraiodothyroaetic acid (tetrac) is a derivative of L-thyroxine with anticancer properties. By multiple molecular mechanisms, tetrac and chemically-modified tetrac induce apoptosis in a variety of human cancer cells in vitro and in xenografts. The anticancer activities of tetrac are initiated at the thyroid hormone analogue receptor on the extracellular domain of plasma membrane integrin αvβ3 (PJ Davis et al., Physiol Rev 101:319-352, 2021). Induction of apoptosis in glioblastoma xenograft with chemically modified tetrac (P-bi-TAT) has yielded 90% in volume of grafts that continues after discontinuation of tetrac. In the present study, we show that human glioblastoma xenograft shrinkage in response to P-bi-TAT is associated with local appearance of phagocytic monocytes and clearance of apoptotic debris (efferocytosis). Primary culture xenograft of glioblastoma cells (GBM 052814, kindly provided by the University of Pittsburgh Medical Center, Department of Neurosurgery) and U87-luc (ATCC, Manassas, VA) xenografts were generated in 5-member groups of nude mice for each tumor cell type and for controls. Five days post-implantation, injection of animals was begun with PBS (control) or P-bi-TAT (10 mg/kg body weight). Injection was continued X21 days and animals were then maintained off-treatment for an additional 21 days. Tumors were harvested, formalin-fixed and slide-mounted, then analyzed by TUNEL assay for apoptosis and by anti-CD68 staining for monocytic macrophage content. Histologic analysis (H&E staining) was also carried out. TUNEL analysis and histopathology of both xenograft models revealed more than 90% apoptotic change with 21-days of P-bi-TAT treatment (P <0.001) and persistence of 40% apoptotic change 3 weeks post-discontinuation of drug (P<0.001 vs. end of treatment change). By H&E histology and CD68 analysis, monocytes accounted for more than 90% of the viable cells after 3 weeks’ drug treatment. Sixty percent of the end-of-treatment monocyte population persisted 3 weeks after discontinuation of P-bi-TAT (P <0.001). Histology revealed negligible cell debris after 3 weeks of drug treatment and at 3 weeks post-discontinuation of P-bi-TAT. Thus, the anticancer/pro-apoptotic action of tetrac-containing P-bi-TAT is associated with efferocytosis that contributes to the frank tumor shrinkage that results from P-bi-TAT treatment of human glioblastoma xenografts. This is the first documentation of efferocytosis regulated from the thyroid hormone analogue receptor on tumor cell integrin αvβ3.
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Ramírez Pérez, Candy. "Primer registro de la familia Agaonidae (Hymenoptera: Chalcidoidea) en la fauna viviente de la Hispaniola." Novitates Caribaea, no. 6 (October 1, 2013): 96–98. http://dx.doi.org/10.33800/nc.v0i6.128.

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Se registra la presencia de la familia Agaonidae (Hymenoptera: Chalcidoidea) para la República Dominicana en base a ejemplares colectados recientemente. Hasta el momento se han identificado los géneros Pegoscapus Cameron, 1906 y Tetrapus Mayr, 1885.
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38

Sengoku, Tetsuya, Yusuke Murata, Chihiro Suzuki, Masaki Takahashi, and Hidemi Yoda. "Synthesis of new chiral lactam-fused pyridine derivatives." RSC Advances 5, no. 90 (2015): 73562–65. http://dx.doi.org/10.1039/c5ra16896a.

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An acid promoted cyclisation of benzylidene-modified tetramic acid and various enamines followed by MnO2 oxidation afforded the corresponding C2-symmetric and unsymmetric lactam-fused pyridines in enantiomerically pure forms.
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39

Stachel, Hans-Dietrich, Hermann Poschenrieder, and Hans Burghard. "Synthese von 5-Alkyliden-3-pyrrolin-2-onen / Synthesis of 5-Alkylidene-3-pyrrolin-2-ones." Zeitschrift für Naturforschung B 41, no. 5 (May 1, 1986): 640–44. http://dx.doi.org/10.1515/znb-1986-0516.

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By reduction of the tetramic acids 1 or their derivatives 5 and 6 with complex borohydrides the pyrrolidinones 2 and 7 are obtained. Dehydration of 2 and 7 leads to the title compounds 3 and 8, respectively.
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40

Lin, Xiaojing, Siwen Yuan, Senhua Chen, Bin Chen, Hui Xu, Lan Liu, Huixian Li, and Zhizeng Gao. "Heterologous Expression of Ilicicolin H Biosynthetic Gene Cluster and Production of a New Potent Antifungal Reagent, Ilicicolin J." Molecules 24, no. 12 (June 18, 2019): 2267. http://dx.doi.org/10.3390/molecules24122267.

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Ilicicolin H is a broad-spectrum antifungal agent targeting mitochondrial cytochrome bc1 reductase. Unfortunately, ilicicolin H shows reduced activities in vivo. Here, we report our effort on the identification of ilicicolin H biosynthetic gene cluster (BGC) by genomic sequencing a producing strain, Neonectria sp. DH2, and its heterologous production in Aspergillus nidulans. In addition, a shunt product with similar antifungal activities, ilicicolin J, was uncovered. This effort would provide a base for future combinatorial biosynthesis of ilicicolin H analogues. Bioinformatics analysis suggests that the backbone of ilicicolin H is assembled by a polyketide-nonribosomal peptide synthethase (IliA), and then offloaded with a tetramic acid moiety. Similar to tenellin biosynthesis, the tetramic acid is then converted to pyridone by a putative P450, IliC. The decalin portion is most possibly constructed by a S-adenosyl-l-methionine (SAM)-dependent Diels-Alderase (IliD).
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41

Schmohl, Kathrin A., Peter J. Nelson, and Christine Spitzweg. "Tetrac as an anti-angiogenic agent in cancer." Endocrine-Related Cancer 26, no. 6 (June 2019): R287—R304. http://dx.doi.org/10.1530/erc-19-0058.

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The thyroid hormones T3 and T4 have emerged as pro-angiogenic hormones with important implications for cancer management. Endogenous circulating hormone levels may help stimulate cancer progression and limit the effectiveness of anticancer therapy, though clinical data remain inconclusive. The capacity of thyroid hormones to modulate angiogenesis is mediated through non-canonical mechanisms initiated at the cell surface receptor integrin αvβ3. This integrin is predominantly expressed on tumour cells, proliferating endothelial cells and tumour stroma-associated cells, emphasising its potential relevance in angiogenesis and tumour biology. Thyroid hormone/integrin αvβ3 signalling results in the activation of intracellular pathways that are commonly associated with angiogenesis and are mediated through classical pro-angiogenic molecules such as vascular endothelial growth factor. The naturally occurring T4 analogue tetrac blocks the pro-angiogenic actions of thyroid hormones at the integrin receptor, in addition to agonist-independent anti-angiogenic effects. Tetrac reduces endothelial cell proliferation, migration and tube formation through a reduction in the transcription of vascular growth factors/growth factor receptors, hypoxia-inducible factor-1α, pro-angiogenic cytokines and a number of other pro-angiogenic genes, while at the same time stimulating the expression of endogenous angiogenesis inhibitors. It further modulates vascular growth factor activity by disrupting the crosstalk between integrin αvβ3 and adjacent growth factor receptors. Moreover, tetrac disrupts thyroid hormone-stimulated tumour recruitment, differentiation and the pro-angiogenic signalling of tumour stroma-associated mesenchymal stem cells. Tetrac affects tumour-associated angiogenesis via multiple mechanisms and interferes with other cancer cell survival pathways. In conjunction with its low toxicity and high tissue selectivity, tetrac is a promising candidate for clinical application.
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42

Schmohl, Kathrin A., Andrea M. Müller, Alexandra Wechselberger, Svenja Rühland, Nicole Salb, Nathalie Schwenk, Heike Heuer, et al. "Thyroid hormones and tetrac: new regulators of tumour stroma formation via integrin αvβ3." Endocrine-Related Cancer 22, no. 6 (August 25, 2015): 941–52. http://dx.doi.org/10.1530/erc-15-0245.

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To improve our understanding of non-genomic, integrin αvβ3-mediated thyroid hormone action in tumour stroma formation, we examined the effects of triiodo-l-thyronine (T3),l-thyroxine (T4) and integrin-specific inhibitor tetrac on differentiation, migration and invasion of mesenchymal stem cells (MSCs) that are an integral part of the tumour's fibrovascular network. Primary human bone marrow-derived MSCs were treated with T3or T4in the presence of hepatocellular carcinoma (HCC) cell-conditioned medium (CM), which resulted in stimulation of the expression of genes associated with cancer-associated fibroblast-like differentiation as determined by qPCR and ELISA. In addition, T3and T4increased migration of MSCs towards HCC cell-CM and invasion into the centre of three-dimensional HCC cell spheroids. All these effects were tetrac-dependent and therefore integrin αvβ3-mediated. In a subcutaneous HCC xenograft model, MSCs showed significantly increased recruitment and invasion into tumours of hyperthyroid mice compared to euthyroid and, in particular, hypothyroid mice, while treatment with tetrac almost completely eliminated MSC recruitment. These studies significantly improve our understanding of the anti-tumour activity of tetrac, as well as the mechanisms that regulate MSC differentiation and recruitment in the context of tumour stroma formation, as an important prerequisite for the utilisation of MSCs as gene delivery vehicles.
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Davis, Paul J., Sandra Incerpi, Hung-Yun Lin, Heng-Yuan Tang, Thangirala Sudha, and Shaker A. Mousa. "Thyroid Hormone and P-Glycoprotein in Tumor Cells." BioMed Research International 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/168427.

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P-glycoprotein (P-gp; multidrug resistance pump 1, MDR1; ABCB1) is a plasma membrane efflux pump that when activated in cancer cells exports chemotherapeutic agents. Transcription of the P-gp gene (MDR1) and activity of the P-gp protein are known to be affected by thyroid hormone. A cell surface receptor for thyroid hormone on integrinαvβ3 also binds tetraiodothyroacetic acid (tetrac), a derivative of L-thyroxine (T4) that blocks nongenomic actions of T4and of 3,5,3′-triiodo-L-thyronine (T3) atαvβ3. Covalently bound to a nanoparticle, tetrac as nanotetrac acts at the integrin to increase intracellular residence time of chemotherapeutic agents such as doxorubicin and etoposide that are substrates of P-gp. This action chemosensitizes cancer cells. In this review, we examine possible molecular mechanisms for the inhibitory effect of nanotetrac on P-gp activity. Mechanisms for consideration include cancer cell acidification via action of tetrac/nanotetrac on the Na+/H+exchanger (NHE1) and hormone analogue effects on calmodulin-dependent processes and on interactions of P-gp with epidermal growth factor (EGF) and osteopontin (OPN), apparently viaαvβ3. Intracellular acidification and decreased H+efflux induced by tetrac/nanotetrac via NHE1 is the most attractive explanation for the actions on P-gp and consequent increase in cancer cell retention of chemotherapeutic agent-ligands of MDR1 protein.
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Ghosh, Swarbhanu, Rostam Ali Molla, Utpal Kayal, Asim Bhaumik, and Sk Manirul Islam. "Ag NPs decorated on a COF in the presence of DBU as an efficient catalytic system for the synthesis of tetramic acids via CO2 fixation into propargylic amines at atmospheric pressure." Dalton Transactions 48, no. 14 (2019): 4657–66. http://dx.doi.org/10.1039/c9dt00017h.

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Ag NPs are decorated at the surface of a COF material TpPa-1 and the resulting Ag@TpPa-1 catalyzes efficiently for the synthesis of tetramic acids from a variety of propargylic amines using CO2 as reagent.
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45

Durach, Christian F., Frank Wiengarten, and Thomas Y. Choi. "Supplier–supplier coopetition and supply chain disruption: first-tier supplier resilience in the tetradic context." International Journal of Operations & Production Management 40, no. 7/8 (July 6, 2020): 1041–65. http://dx.doi.org/10.1108/ijopm-03-2019-0224.

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PurposeThe present study considers disruption in the buyer–supplier–supplier triad. This triad has a common second-tier supplier as the disruption source, which gives us the tetradic context. The goal is to advance the knowledge on how a first-tier supplier's resilience against lower-tier disruptive events can be developed through horizontally connecting with the other first-tier supplier and how the buyer can benefit from its first-tier suppliers' resilience capability.Design/methodology/approachData from 33 triads was collected and analyzed.FindingsAs predicted, coopetition between two first-tier suppliers increases the first-tier supplier's capability to be resilient to disruptive events emanating from a lower tier source. However, contrary to initial theorization, the first-tier supplier's resilience capability affects the buyer's performance during disruptive events negatively. With increasing buyer–supplier social bonds, this negative relationship can partly be alleviated.Research limitations/implicationsAnalyzing resilience within a triad to a disruption in the tetradic context reveals unexpected dynamics. Individual supplier's resilience may have a negative impact on the buyer's resilience in certain disruption events.Practical implicationsThe buyer can increase collective suppliers' resilience through establishing horizontal links. To prevent becoming a victim of the supplier's resilience in the event of a second-tier disruption, a buyer needs to become a member of the supplier's relational network.Originality/valueWe propose that resilience can rest with the suppliers. This observation has implications for the buyer when selecting and coordinating suppliers. Further, it considers a context beyond a triad by venturing into the tetradic context. We anticipate more studies in tetrads in future and this study can serve as a bridge.
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46

Schwing, R., E. Meaux, A. Piseddu, L. Huber, and R. Noë. "Kea, Nestor notabilis, achieve cooperation in dyads, triads, and tetrads when dominants show restraint." Learning & Behavior 49, no. 1 (February 2, 2021): 36–53. http://dx.doi.org/10.3758/s13420-021-00462-9.

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AbstractAnimal cooperation in the wild often involves multiple individuals that must tolerate each other in close proximity. However, most cooperation experiments in the lab are done with two animals, that are often also physically separated. Such experiments are useful for answering some pertinent questions, for example about the understanding of the role of the partner and strategies of partner control, but say little about factors determining successful cooperation with multiple partners in group settings. We explored the influence of dominance, rank distance, tolerance, affiliation, and coordination by testing kea parrots with a box requiring two, three, or four chains to be pulled simultaneously to access food rewards. The reward could be divided unevenly, but not monopolized completely. Eventually dyadic, triadic, and tetradic cooperation tasks were solved, showing that non-human animals are capable of tetradic cooperation in an experimental setup. Starting with two chains, we found that in a dyad monopolization of the box by the highest-ranking bird was the largest obstacle preventing successful cooperation. High-ranking birds learned to restrain themselves from monopolizing the box during a single session in which monopolization was hindered by the presence of a large number of birds. Thereafter, restraint by dominants remained the strongest factor determining success in the first trial in dyadic, triadic, and tetradic setups. The probability of success increased with the degree of restraint shown by all dominant subjects present. Previous experience with the task contributed to success in subsequent sessions, while increasing rank distance reduced success notably in the four-chain setup.
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Nana, André Wendindondé, Yu-Tang Chin, Chi-Yu Lin, Yih Ho, James A. Bennett, Ya-Jung Shih, Yi-Ru Chen, et al. "Tetrac downregulates β-catenin and HMGA2 to promote the effect of resveratrol in colon cancer." Endocrine-Related Cancer 25, no. 3 (March 2018): 279–93. http://dx.doi.org/10.1530/erc-17-0450.

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The molecular pathogenesis of colorectal cancer encompasses the activation of several oncogenic signaling pathways that include the Wnt/β-catenin pathway and the overexpression of high mobility group protein A2 (HMGA2). Resveratrol – the polyphenolic phytoalexin – binds to integrin αvβ3 to induce apoptosis in cancer cellsviacyclooxygenase 2 (COX-2) nuclear accumulation and p53-dependent apoptosis. Tetraiodothyroacetic acid (tetrac) is a de-aminated derivative ofl-thyroxine (T4), which – in contrast to the parental hormone – impairs cancer cell proliferation. In the current study, we found that tetrac promoted resveratrol-induced anti-proliferation in colon cancer cell lines, in primary cultures of colon cancer cells, andin vivo. The mechanisms implicated in this action involved the downregulation of nuclear β-catenin and HMGA2, which are capable of compromising resveratrol-induced COX-2 nuclear translocation. Silencing of either β-catenin or HMGA2 promoted resveratrol-induced anti-proliferation and COX-2 nuclear accumulation which is essential for integrin αvβ3-mediated-resveratrol-induced apoptosis in cancer cells. Concurrently, tetrac enhanced nuclear abundance of chibby family member 1, the nuclear β-catenin antagonist, which may further compromise the nuclear β-catenin-dependent gene expression and proliferation. Taken together, these results suggest that tetrac targets β-catenin and HMGA2 to promote resveratrol-induced-anti-proliferation in colon cancers, highlighting its potential in anti-cancer combination therapy.
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Mousa, Shaker, Gennadi Glinsky, Hung-Yun Lin, Osnat Ashur-Fabian, Aleck Hercbergs, Kelly Keating, and Paul Davis. "Contributions of Thyroid Hormone to Cancer Metastasis." Biomedicines 6, no. 3 (August 22, 2018): 89. http://dx.doi.org/10.3390/biomedicines6030089.

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Acting at a cell surface receptor on the extracellular domain of integrin αvβ3, thyroid hormone analogues regulate downstream the expression of a large panel of genes relevant to cancer cell proliferation, to cancer cell survival pathways, and to tumor-linked angiogenesis. Because αvβ3 is involved in the cancer cell metastatic process, we examine here the possibility that thyroid hormone as l-thyroxine (T4) and the thyroid hormone antagonist, tetraiodothyroacetic acid (tetrac), may respectively promote and inhibit metastasis. Actions of T4 and tetrac that are relevant to cancer metastasis include the multitude of synergistic effects on molecular levels such as expression of matrix metalloproteinase genes, angiogenesis support genes, receptor tyrosine kinase (EGFR/ERBB2) genes, specific microRNAs, the epithelial–mesenchymal transition (EMT) process; and on the cellular level are exemplified by effects on macrophages. We conclude that the thyroid hormone-αvβ3 interaction is mechanistically linked to cancer metastasis and that modified tetrac molecules have antimetastatic activity with feasible therapeutic potential.
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49

Matusitz, Jonathan. "Applying McLuhan’s tetradic framework to the effects of 9/11 on US media reports and depictions of Muslims." Journal of Arab & Muslim Media Research 13, no. 2 (September 1, 2020): 179–94. http://dx.doi.org/10.1386/jammr_00018_1.

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This article applies McLuhan’s tetradic framework to the impact of 9/11 on US media reports and portrayals of Muslims. The tetradic framework posits that transformations in media and world life happen through four fundamental steps. All forms of media (1) intensify specific aspects of media culture while, simultaneously, (2) making other characteristics of media culture obsolete. At some point, people tend to (3) discover new things about aspects in media culture that were ignored in the past (i.e. which obsolete aspects of culture do media retrieve?). Finally, (4) with this rise in information-seeking and discovery, media culture is experiencing continuous modification. Stated differently, the media go through a reversal when pushed too far or extended beyond the limits of their capacity. Overall, this analysis is able to inform readers on the full complexity of the long-term development of people’s perceptions of Muslims as a result of the constant metamorphosis of the media.
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Crisp, GT, and MP Collis. "Metathesis of Functionalized Alkenes. Synthesis of Insect Pheromones." Australian Journal of Chemistry 41, no. 6 (1988): 935. http://dx.doi.org/10.1071/ch9880935.

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Abstract:
The ability of substituted phenoxy complexes of tungsten to effect metathesis of both functionalized and non-functionalized terminal alkenes has been investigated. This methodology has been applied to the synthesis of the insect pheromones tetradec-9-en-1-yl acetate, dodec-7- en-1-yl acetate and tricos-9-ene.
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