Veterinary and Agricultural Sciences Collected Works - Research Publications

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    Effect of a polyphenol-rich plant matrix on colonic digestion and plasma antioxidant capacity in a porcine model
    Gu, C ; Howell, K ; Padayachee, A ; Comino, T ; Chhan, R ; Zhang, P ; Ng, K ; Cottrell, JJ ; Dunshea, FR (Elsevier, 2019-06-01)
    Altering cellular structure by reducing the particle size and applying heat may enhance the release of polyphenols from the plant cell matrix. The released polyphenols could ameliorate the impacts of a high-fat diet. Using a pig model in a 2 × 2 cross-over trial, we tested the effects of processing on the bioaccessibility of polyphenols in the diet, using low- and high-fat diets supplemented with raw and diced or cooked and pureed black carrots. Raw diced black carrots resulted in higher average particle size in the digesta of all gastrointestinal compartments and higher total and major short chain fatty acids in the descending colon. Supplementing the diet with raw and diced carrots also increased the colonic bacterial counts but with limited effects on gut microbiome diversity. The presence of carrots did not mitigate the negative impacts of decreased plasma antioxidant capacity and high atherogenic index induced by a high-fat diet.
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    Effects of macro-nutrient, micro-nutrient composition and cooking conditions on in vitro digestibility of meat and aquatic dietary proteins
    Luo, J ; Taylor, C ; Nebl, T ; Ng, K ; Bennett, LE (ELSEVIER SCI LTD, 2018-07-15)
    Animal and aquatic meats represent important sources of dietary protein and micro-nutrients. Although red and processed meats carry some risks for human health, sensory and nutritional advantages drive meat consumption. Therefore, it is important to understand how meat processing and cooking influence healthiness. The research aim was to investigate relationships of meat composition (proximates, amino acids and minerals) and cooking conditions (raw, 90 s microwave, 200 °C oven for 10 or 30 min) on protein digestibility, for a selection of four animal (beef, chicken, pork, kangaroo) and four aquatic meats (salmon, trout, prawn, oyster). Lean meats were minced before cooking followed by in vitro gastro-intestinal digestion and analysed for progress of hydrolysis, and size ranges of peptides using MALDI-TOF-MS. Correlation matrix analysis between compositional and functional parameters indicated that digestibility was significantly linked with protein and metal concentrations, likely reflecting moisture-dependent solubility and inter-mixing of sarcoplasmic metallo-proteins and insoluble myofibrillar proteins.
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    PHOTOAFFINITY-LABELING OF CHLOROQUINE-BINDING PROTEINS IN PLASMODIUM-FALCIPARUM
    FOLEY, M ; DEADY, LW ; NG, K ; COWMAN, AF ; TILLEY, L (AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC, 1994-03-04)
    A photoreactive analog of chloroquine, N-(4-(4-diethylamino-1-methylbutylamino)quinolin-6-yl)-4- azi do-2- hydroxybenzamide (referred to as ASA-Q), has been synthesized and shown to mimic the action of chloroquine in possessing substantial antimalarial activity against a chloroquine-sensitive strain of Plasmodium falciparum. As for chloroquine, ASA-Q is less effective at killing drug-resistant strains of malaria, and the resistance can be modulated using the reagent verapamil. ASA-Q has been radiolabeled with Na125I and used as a photoaffinity probe for labeling chloroquine-binding proteins in malaria-infected erythrocytes. Two proteins have been identified with apparent molecular masses of 42 and 33 kDa in both chloroquine-sensitive and chloroquine-resistant strains of malaria. Photoaffinity labeling of the two proteins by iodo-ASA-Q was competitively inhibited by an excess of unlabeled chloroquine. The structurally related antimalarials amodiaquine and quinine also inhibited labeling of the two proteins, while verapamil and doxycycline had no effect. We suggest that the two labeled proteins are the macromolecular targets of chloroquine action in malaria parasites.
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    Selenium-Enriched Agaricus bisporus Mushroom Protects against Increase in Gut Permeability ex vivo and Up-Regulates Glutathione Peroxidase 1 and 2 in Hyperthermally-Induced Oxidative Stress in Rats
    Maseko, T ; Dunshea, FR ; Howell, K ; Cho, H-J ; Rivera, LR ; Furness, JB ; Ng, K (MDPI AG, 2014-06-01)
    Dietary effects of organic Se supplementation in the form of Se-enriched Agaricus bisporus mushroom on ileal mucosal permeability and antioxidant selenoenzymes status in heat induced oxidative stress in rats were evaluated. Acute heat stress (40 °C, 21% relative humidity, 90 min exposure) increased ileum baseline short circuit current (Isc; 2.40-fold) and epithelial conductance (Ge; 2.74-fold). Dietary supplementation with Se-enriched A. bisporus (1 µg Se/g feed) reduced (p < 0.05) ileum Isc and Ge during heat stress to 1.74 and 1.91 fold, respectively, indicating protection from heat stress-induced mucosal permeability increase. The expression of ileum glutathione peroxidase (GPx-) 1 and 2 mRNAs were up-regulated (p < 0.05) by 1.90 and 1.87-fold, respectively, for non-heat stress rats on the Se-enriched diet relative to the control. The interplay between heat stress and dietary Se is complex. For rats on the control diet, heat stress alone increased ileum expression of GPx-1 (2.33-fold) and GPx-2 (2.23-fold) relative to thermoneutral conditions. For rats on the Se-enriched diet, heat stress increased (p < 0.05) GPx-1 expression only. Rats on Se-enriched + α-tocopherol diet exhibited increased expression of both genes (p < 0.05). Thus, dietary Se-enriched A. bisporus protected against increase in ileum permeability and up-regulated GPx-1 and GPx-2 expression, selenoenzymes relevant to mitigating oxidative stress.