Publications by authors named "J A Coverdale"

322 Publications

Effects of crude protein content on intake and digestion of coastal bermudagrass hay by horses.

Transl Anim Sci 2021 Jul 29;5(3):txab073. Epub 2021 Apr 29.

Department of Animal Science, Texas A&M University, College Station, TX 77843, USA.

This study was conducted to determine the effects of forage crude protein () level on intake and digestion of Coastal bermudagrass hay by horses. Four cecally fistulated geldings were used in a 4 × 4 Latin square design with four treatments and four periods. Horses were fed one of four Coastal bermudagrass hays consisting of 7%, 10%, 13%, or 16% CP during each of the four 15-d periods. Intake and apparent digestibility were determined for each horse at the end of each period by total fecal collection. In addition, cecal fluid and blood samples were collected on the last day of each period for the determination of cecal ammonia, cecal pH, plasma urea nitrogen (), and plasma glucose concentrations. Data were analyzed using PROC MIXED of SAS. CP concentration of Coastal bermudagrass hay influenced equine intake and digestion. Increasing CP concentration linearly increased digestible organic matter intake () from 3.79 to 5.98 kg/d for 7% and 16% CP hay, respectively ( = 0.04). Furthermore, as the forage CP level increased, CP intake increased linearly ( < 0.01). The forage CP level had no effect on forage dry matter intake. Quadratic effects ( ≤ 0.05) were observed for forage OM, neutral detergent fiber, acid detergent fiber, and digestible energy. Overall digestibility was lowest for the 7% CP hay and highest for the 10% CP hay. Cecal pH remained above 6.62 irrespective of treatment and time, indicating that cecal pH was suitable for microbial growth. As the forage CP level increased, cecal ammonia concentration increased linearly from 0.03 mM for the 7% to 1.74 mM for the 16% CP hay ( < 0.01). Concentration of plasma glucose also linearly increased ( = 0.04) from 68.77 to 73.68 mg/dL as CP concentration increased from 7% to 16% CP. PUN exhibited a quadratic effect as concentration increased ( < 0.01) from 4.34 to 5.61 mM for the 7% and 16% CP hays, respectively. Overall, the 10% CP hay had the highest digestibility due to its higher OM digestion. As forage OMI increased, digestible OM increased until physiological capacity for digestion is exceeded. At that point, digestion will decline with the decrease in OMI, explaining the lower digestion for other forages fed.
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http://dx.doi.org/10.1093/tas/txab073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8379517PMC
July 2021

John Gregory's medical ethics elucidates the concepts of compassion and empathy.

Med Teach 2021 Aug 9:1-5. Epub 2021 Aug 9.

Professor and Departmental Chair of Obstetrics and Gynecology, Associate Dean for International Education, Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY, USA.

Purpose: This paper draws on eighteenth-century British medical ethics to elucidate compassion and empathy and explains how compassion and empathy can be taught, to rectify their frequent conflation.

Compassion In The History Of Medical Ethics: The professional virtue of compassion was first described in eighteenth-century British medical ethics by the Scottish physician-ethicist, John Gregory (1724-1773) who built on the moral psychology of David Hume (1711-1776) and its principle of sympathy.

Compassion And Empathy Defined: Compassion is the habitual exercise of the affective capacity to engage, with self-discipline, in the experience of the patient and therefore become driven to provide effective care for the patient. Empathy is the habitual exercise of the cognitive capacity to imagine the experience of patient and to have reasons to care for the patient. There are rare clinical circumstances in which empathy should replace compassion, for example, in responding to abusive patients. Because the abstract concepts of medical ethics are translated into clinical practice by medical educators, we identify the pedagogical implications of these results by setting out a process for teaching compassion and empathy.

The Task Ahead: Eighteenth-century British medical ethics provides a clinically applicable, philosophical response to conflation of the moral virtue of compassion and the intellectual virtue of empathy and applying them clinically.
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http://dx.doi.org/10.1080/0142159X.2021.1960295DOI Listing
August 2021

Effect of maternal overnutrition on predisposition to insulin resistance in the foal: Foal skeletal muscle development and insulin signaling.

Domest Anim Endocrinol 2021 Oct 2;77:106648. Epub 2021 Jul 2.

Department of Animal Science, Texas A&M University, College Station, Texas 77843. Electronic address:

Skeletal muscle plays an integral role in the ability of a horse to perform at high levels. Shifts in skeletal muscle development in response to maternal plane of nutrition may have substantial and lasting impacts on athletic performance and whole-body metabolism. Therefore, sixteen Quarter Horse mares were used in a completely randomized design and maintained at a body condition score (BCS) 6 until start of third trimester. On d 235 of gestation, mares were randomly assigned to receive one of two dietary treatments with a diet formulated to meet requirements during late gestation (CON; n = 8), and an overfed diet (HIGH; n = 8) where mares received an additional 40% above CON. Five h after parturition, foals were euthanized, and gluteus medius, triceps brachii, and semitendinosus were harvested for analyses. Gene expression was determined by qPCR and western immunoblotting was used to quantify total and phosphorylated forms of proteins involved in skeletal muscle metabolism with tubulin as the loading control. All data were analyzed using PROC MIXED of SAS. Foals from HIGH mares exhibited larger skeletal muscle fibers by area (P <0.05), and a shift in muscle fiber development towards type I slow twitch muscle fibers (P <0.05). Relative expression of glucose transporter 4 (GLUT4) was lower in HIGH foals compared to CON in gluteus medius (P = 0.05). Insulin receptor isoform B (INSR-B) and insulin-like growth factor 1 receptor (IGF1R) were greater in triceps brachii of HIGH foals compared to CON (P ≤ 0.03). Insulin receptor isoform A (INSR-A), however, tended to be lower in triceps brachii of HIGH compared to CON (P = 0.10). Ratios of phosphorylated to total extracellular signal-regulated protein kinase 1/2 (ERK1/2) and c-June N-terminal kinase (JNK) were higher in HIGH foals compared to CON (P ≤0.04) in gluteus medius. There were no differences observed for phosphorylated to total protein ratios in semitendinosus and triceps brachii muscles; however, total ERK1/2 tended to be elevated (P <0.10) in semitendinosus from CON foals compared to HIGH. There was no difference in phosphorylated or total protein kinase B (AKT) (P >0.14). These data indicate hypertrophy of skeletal muscle fibers and a shift towards type I slow twitch fibers in HIGH foals. Furthermore, this study identifies muscle specific changes in gene expression and downstream insulin receptor signaling, which may contribute to future metabolic abnormalities in response to maternal overnutrition.
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http://dx.doi.org/10.1016/j.domaniend.2021.106648DOI Listing
October 2021

Ligand-centred redox activation of inert organoiridium anticancer catalysts.

Chem Sci 2020 May 15;11(21):5466-5480. Epub 2020 May 15.

Department of Chemistry, University of Warwick Coventry CV4 7AL UK

Organometallic complexes with novel activation mechanisms are attractive anticancer drug candidates. Here, we show that half-sandwich iodido cyclopentadienyl iridium(iii) azopyridine complexes exhibit potent antiproliferative activity towards cancer cells, in most cases more potent than cisplatin. Despite their inertness towards aquation, these iodido complexes can undergo redox activation by attack of the abundant intracellular tripeptide glutathione (GSH) on the chelated azopyridine ligand to generate paramagnetic intermediates, and hydroxyl radicals, together with thiolate-bridged dinuclear iridium complexes, and liberate reduced hydrazopyridine ligand. DFT calculations provided insight into the mechanism of this activation. GS attack on the azo bond facilitates the substitution of iodide by GS, and leads to formation of GSSG and superoxide if O is present as an electron-acceptor, in a largely exergonic pathway. Reactions of these iodido complexes with GSH generate complexes, which are catalysts for GSH oxidation. The complexes promoted elevated levels of reactive oxygen species (ROS) in human lung cancer cells. This remarkable ligand-centred activation mechanism coupled to redox reactions adds a new dimension to the design of organoiridium anticancer prodrugs.
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http://dx.doi.org/10.1039/d0sc00897dDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8159363PMC
May 2020

Organoruthenium Complexes with Benzo-Fused Pyrithiones Overcome Platinum Resistance in Ovarian Cancer Cells.

Cancers (Basel) 2021 May 20;13(10). Epub 2021 May 20.

Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia.

Drug resistance to existing anticancer agents is a growing clinical concern, with many first line treatments showing poor efficacy in treatment plans of some cancers. Resistance to platinum agents, such as cisplatin, is particularly prevalent in the treatment of ovarian cancer, one of the most common cancers amongst women in the developing world. Therefore, there is an urgent need to develop next generation of anticancer agents which can overcome resistance to existing therapies. We report a new series of organoruthenium(II) complexes bearing structurally modified pyrithione ligands with extended aromatic scaffold, which overcome platinum and adriamycin resistance in human ovarian cancer cells. The mechanism of action of such complexes appears to be unique from that of cisplatin, involving G cell cycle arrest without generation of cellular ROS, as is typically associated with similar ruthenium complexes. The complexes inhibit the enzyme thioredoxin reductase (TrxR) in a model system and reduce cell motility towards wound healing. Importantly, this work highlights further development in our understanding of the multi-targeting mechanism of action exhibited by transition metal complexes.
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http://dx.doi.org/10.3390/cancers13102493DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8160969PMC
May 2021
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