Browsing by Author "Thatcher, Craig D."

Now showing 1 - 18 of 18
  • Thumbnail Image
    Analysis of newborn calf body measurements and relationship of calf shape to sire breeding values for birth weight and calving ease
    Nugent, Russell Arthur (Virginia Tech, 1990)
    These studies were conducted to define calf body shape, to test for relationships between calf shape and sire expected progeny differences for birth weight (BWTEPD) and first-calf calving ease (CEEPD) and to evaluate the efficacy of calf shape as a selection criterion for reduction of calving difficulty. Birth weight (BW), head circumference (HC), hip width (HW), shoulder width, body length (BL), cannon circumference (CC), cannon length (CL) and heart girth (HG) were measured at birth on 1,016 calves sired by Angus, Polled Hereford and Simmental bulls. In the Angus- and Polled Hereford-sired calves, sire effects were present for BW-adjusted residuals of CC. Additionally, HW, BL and HG residuals differed among half-sib groups for the Polled Hereford-sired calves. Thus, calf body measure differences independent of BW were in part attributable to sire. Multivariate factor analysis was used to identify underlying skeletal width and frame dimensions of calf shape in both breeds. After adjustment of body measures for differences in BW, a positive relationship of BWTEPD with HC and CC and a negative relationship between CEEPD and CC existed. Further adjustment for BWTEPD removed effects of CEEPD on CC. Thus, BWTEPD influenced calf shape independent of BW, but shape was not related to CEEPD independent of BWTEPD. Simmental bulls were divergently selected on CEEPD relative to BWTEPD so that body measures of calves from sires whose progeny tended to be born with more or with less dystocia than expected from BWTEPD could be obtained. Differences in CL and CC at constant BW were in part attributable to sire. Underlying shape factors were similar to those of the other breeds. Sire BWTEPD was positively related to CC and HC independent of BW. However, a relationship between body measures and CEEPD existed only at constant BW and BWTEPD. Calf shape independent of BW was also not different among calves born unassisted and assisted. Estimates of heritability, repeatability and birth to weaning relationships for each BW-residual body measure were generally not significant. Overall, sire BWTEPD was related to calf shape independent of BW. However, increases in skeletal dimensions were not related to either observed calving difficulty nor sire CEEPD independent of BW. Selection for reduced calving difficulty should not be based on calf body shape.
  • Thumbnail Image
    An Assessment of the Effects of Oxidative Stress and Dietary Antioxidants on Toxin-Induced Dilated Cardiomyopathy in the Turkey (Meleagris gallopavo)
    Gyenai, Kwaku Barima (Virginia Tech, 2009-12-16)
    Dilated cardiomyopathy (DCM) or round heart disease is a muscle disease of the heart characterized by left ventricular dilatation and abnormal systolic and diastolic ventricular function. In animals, including turkeys and humans, DCM is a major cause of morbidity and mortality that results in heart failure. In the turkey, DCM can be idiopathic or induced. Since idiopathic or spontaneous DCM occurs in about 2-4 % of normal turkeys, it is of significant concern to the poultry industry. This dissertation was designed to increase our understanding of the pathophysiology of DCM in commercial turkeys. Specific objectives included: evaluating the influence of dietary selenium (Se) and vitamin E on poults fed toxic levels of furazolidone (Fz). Evaluating differences among reciprocal crosses of turkey varieties in susceptibility to a toxic level of Fz that induces DCM were used to assess the role of genetics in DCM. Using glutathione (GSH), glutathione peroxidase (GPx), malondialdehyde (MDA), and plasma uric acid (PUA) as biomarkers, oxidative stress (OS) levels were evaluated. Oxidative stress was also evaluated in poults fed diets containing varying concentration and combinations of vitamin E (0, 50 and 100 IU/kg) and Se (0.0, 0.3 and 0.5 mg/kg). Results from echocardiography measurements at four weeks of age, for poults fed toxic levels of Fz, showed the Narragansett x Bourbon Red reciprocal cross had the lowest internal-diastolic (LVIDd) and systolic dimensions (LVISd), while the Bourbon Red x Narragansett reciprocal cross had the largest LVIDd and LVISd. Left ventricular internal-diastolic and systolic dimension were lower for cross bred than parental poults. In treatment poults, heterosis for ventricular dilation was most significant for Bourbon Red x Narragansett cross. The data suggest that reciprocal crosses respond differently to toxin that induces DCM and genetics may influence a turkey's response to toxic levels of Fz that causes DCM. Results from OS measurements in poults fed normal and those fed normal diets with Fz at two weeks of age, showed no significant differences in MDA and GPx levels. PUA and GSH levels were however significantly increased for poults fed Fz-containing diets. At four weeks of age, no differences were observed for MDA and GPx measurements between poults fed normal and Fz-containing diets. PUA levels increased for poults fed normal diets with Fz, while GSH levels increased only for those fed normal diets. Differences between poults fed normal and Fz-containing diets were significant for GPx measurements. Results of this study showed that, feeding diets with Fz does not increase OS. Measure of the influence of feeding diets supplemented with different concentrations and combinations of Se and vitamin E to poults fed either normal or normal diets with Fz at two and four wks of age, showed higher MDA levels for poults fed Fz-containing diets supplemented with 0.3 mg/kg Se and 100 IU/kg vitamin E. For antioxidant biomarkers, GPx activity were increased for poults fed normal diets with Fz supplemented with 0.5 mg/kg Se and those fed 100 IU/kg vitamin E. Poults fed normal diets supplemented with 100 IU/kg vitamin E had the highest GPx. PUA levels were higher for poults fed normal diets with Fz supplemented with 0.5 mg/kg Se at two wks of age. At four wks of age, PUA concentrations were higher for poults fed Fz-containing diets supplemented with 100 IU/kg vitamin E. Increased PUA were also observed for poults fed diets supplemented with 0.5 mg/kg Se and 50 IU/kg vitamin E and 0.5 mg/kg and 100 IU/kg vitamin E. Poults fed diets supplemented with 50 and 100 IU/kg vitamin E had the highest GSH at two wks of age. Measurements taken at 2 wks of age, for poults fed normal diets supplemented with different concentrations and combinations of Se and vitamin E had increased GSH levels when compared with those fed diets with Fz at four wks of age. In this study, we showed that supplementation of poults fed normal diets with Fz with different concentrations and combinations of Se and vitamin E did not reduce DCM at 2 wks of age. However, at 4 wks of age, though DCM was not decreased by feeding diets supplemented with different concentrations and combinations of Se and vitamin E, reduced oxidant and antioxidant biomarkers were observed.
  • Thumbnail Image
    Biomarkers of oxidative stress and inflammation in biological samples collected from recurrent airway obstruction (RAO)-affected horses and their controls
    Tan, Rachel Hsing Hsing (Virginia Tech, 2008-03-12)
    Multiple biomarkers of oxidative stress have been measured and used in human medicine to diagnose and monitor airway disease. The purpose of the study was to determine if similar relationships existed between inflammatory and oxidative stress biomarkers in exhaled breath condensate (EBC), bronchoalveolar lavage fluid (BALF), red blood cells, white blood cells, and plasma; and cytokine expression in airway inflammatory cells and mucosal biopsies of RAO-affected horses and their controls. Sixteen horses in pairs were used: 8 non-RAO-affected (controls) and 8 RAO-affected horses. Samples from all horses were collected at remission (S1), during environmental challenge (S2) and at recovery (S3). RAO-affected horses had significant alterations in cellular glutathione peroxidase (cGPx) activity, ascorbic acid and pH in a number of biological samples. Concentrations of 8-isoprostanes, isofurans, amino acids and mRNA expression of interleukin 4 (IL4), gamma interferon (INFγ), inducible nitric oxide synthase (iNOS), extracellular glutathione peroxidase (GPx-3), and cytosolic superoxide dismutase (SOD-1) were not significantly different or were at the limits of detection. Conductivity was measured and assessed as a potential correctional factor for respiratory fluid dilution. The alterations in biomarker concentrations demonstrate that oxidative stress is an important component of airway inflammation in RAO-affected horses. Further research is warranted in the use of biomarkers and the effects of dietary interventions.
  • Thumbnail Image
    Body composition of dogs determined by carcass composition analysis, deuterium oxide dilution, subjective and objective morphometry, and bioelectrical impedance
    Burkholder, William Joseph (Virginia Tech, 1994-05-16)
    Prediction of body composition was assessed in thirty-eight female and thirty-seven male random source dogs using in vivo methods of deuterium oxide dilution, subjective and objective morphometry, bioelectrical impedance and ultrasound, either separately or in various combinations. Carcass composition determined by chemical analyses of carcass homogenates served as criterion measures of body composition. Dogs were selected based on gender, body weight and body condition score. Body weight ranged from 7.3 to 34.5 kilograms (kg), subdivided into 4.5 kg increments with 6 female and 6 male dogs per increment. Body condition was categorized as thin, optimum or obese using a defined criteria, body condition scoring system (subjective morphometry) with 12 female and 12 male dogs per body condition category. Selection criteria produced 18 body weight condition groups with 2 female and 2 male dogs per group. One additional male and 2 female dogs were included for economic and ethical reasons. Equations to predict carcass composition from in vivo measurements were derived using standard regression techniques. Influence diagnostics, residual analysis and data splitting were used to validate predictive equations. Predictions from deuterium oxide dilution produced the most precise estimates of body composition. Average standard errors of estimation (SEE) from deuterium equations were 1.3, 1.8, 1.0, and 0.4 percent for percentages of body moisture, fat, protein and ash, respectively, and 0.39, 0.57,0.21 and 0.08 kg for absolute quantities of moisture, fat, protein and ash, respectively. Morphometry produced the most imprecise, but economical, estimates. Average SEE from morphometry equations for proportions were 3.0, 4.0, 1.3, and 0.4 percent, and 0.9, 0.9, 0.3 and 0.07 kg for absolute quantities of moisture, fat, protein and ash, respectively. Subjective morphometry could estimate body fat with an average SEE of 3.4 percent and correctly categorized 75 percent of the dogs. Bioelectrical impedance and ultrasound produced predictions with average SEE intermediate to deuterium and morphometry. Bioelectrical impedance was equivalent to deuterium dilution on the basis of cost per unit improvement in SEE, but ultrasound was not cost effective.
  • Thumbnail Image
    Can isoprostanes be used to predict survival in horses with colic?
    Noschka, Erik (Virginia Tech, 2010-11-09)
    Approximately 4% of horses suffer from one colic episode per year. The outcome is fatal in 11% of cases. F2-isoprostanes are the "gold standard" for assessment of oxidative stress in vivo and have been used extensively to quantify lipid peroxidation in association with risk factors in various diseases in humans. Because horses with colic may have intestinal ischemia and/or inflammation characterized by oxidative stress and increased production of isoprostanes, measurement of isoprostane concentrations in colicky horses may be of clinical value. The purpose of this study was to gather preliminary data on the feasibility of using urine isoprostane concentrations as an early screening tool for the severity of colic and to determine the need for surgery. The long term goal of this investigation is to reduce the number of deaths due to colic by developing a stall-side test capable of identifying horses needing surgery as early as possible and expediting their timely referral. We hypothesized that urine isoprostanes and isoprostane metabolites would be significantly higher in horses with colic compared to normal horses and that they can be used an indicator for the need for surgical intervention. Urine samples were collected from 42 normal horses and 38 horses with colic (21 medical and 22 surgical). Urine isoprostane and isoprostane metabolite concentrations were measured by mass spectrometry and normalized by urine creatinine (Cr) concentrations. Statistical analysis was performed using a one way ANOVA (Tukey's post-hoc comparison) and a 2 sample t-test. Significance was set at P<0.05. Mean (± SD) concentrations of isoprostanes and isoprostane metabolites were significantly higher in urine samples of horses with colic (2.94 ± 1.69 ng/mg Cr and 0.31 ± 0.22 ng/mg Cr, respectively) compared to healthy horses (1.89 ± 1.39 ng/mg Cr and 0.22 ± 0.08 ng/mg Cr, respectively). Urine isoprostane metabolite concentrations were significantly higher in horses undergoing surgery (0.38 ± 0.28 ng/mg Cr) compared to healthy control horses and medically treated colic horses (0.26 ± 0.11 ng/mg Cr). Non-survivors had significantly higher mean urine isoprostane metabolite concentrations (0.47 ± 0.39 ng/mg Cr) compared to healthy control horses and surviving colic horses (0.29 ± 0.24 ng/mg Cr). Since urinary concentrations of isoprostane metabolites are increased in horses suffering from colic and in non-survivor colic horses, the measurement of urine concentrations of isoprostane metabolites may be an important prognostic indicator in equine colic.
  • Thumbnail Image
    Copper supplementation and monocyte function in growing beef calves
    Saker, Korinn Edna (Virginia Tech, 1995)
    The effect of dietary copper (Cu) supplementation with Cu-Sulfate (CuSO₄) or Cu-Lysine (CuLy) on Cu status and bovine monocyte function was evaluated through a series of experiments. Initially, two in vitro techniques, immunomagnetic (IM) and culture flask adherence (CF), were compared for isolation of a viable, homogeneous monocyte population. The CF technique for monocyte isolation resulted in both a greater number of cells exhibiting phagocytic activity, as well as, an increased phagocytic capacity compared to monocytes recovered by the IM technique. Culture flask adherence appears to be an efficient technique for isolation of a viable, homogeneous population of bovine monocytes. Copper status and monocyte function were evaluated in beef calves supplemented with Cu over a 2 year study period. Fifty-four weaned calves were allotted to one of three Cu treatment groups in a 150 d feeding trial, Plasma Cu concentration was increased in CuLy-supplemented calves over controls and CuSO₄-supplemented calves on d 42, 84, and 126. Calves supplemented with Cu had increased ceruloplasmin activity on d 84, 126, and 150 as compared to controls. Hepatic Cu measured on d 150 was decreased in controls compared to Cu-supplemented calves. Monocyte cell number and function from CuLy-supplemented calves showed increased phagocytosis on d 84 and 126 and increased oxidative burst on d 42 and 126 compared to controls. Dietary Cu supplementation was repeated using 45 calves in a 120 d study. CuLy-supplemented heifers had increased major histocompatibility complex (MHC) class II expression on d 68, 82 and 110 compared to CuSO₄-supplemented and control group heifers. Heifers supplemented with Cu had increased plasma Cu concentrations on d 82 and 110 compared to controls. The effect of vaccination on monocyte function was evaluated in Cu-supplemented beef heifers. Vaccination with B. abortus Strain 19 increased monocyte oxidative burst, phagocytic activity, and MHC class II expression in heifers. Copper supplementation and source of Cu supplement influenced monocyte response to vaccination. Monocyte response appeared to be higher in CuLy-supplemented heifers after vaccination compared to CuSO₄-supplemented and control heifers.
  • Thumbnail Image
    Economic impacts of the Virginia-Maryland Regional College of Veterinary Medicine on the Commonwealth of Virginia
    Kshirsagar, Shukla (Virginia Tech, 1994-01-15)
    This thesis estimates the economic impacts of the Virginia-Maryland Regional College of Veterinary Medicine on the Commonwealth of Virginia. Two types of economic impacts were measured. First, the short term impacts were assessed, using the input-output model for the Commonwealth of Virginia. Operating expenditures of the college were entered into the model as a change in final demand and the multiplier effects of these expenditures were measured. Second, long run benefits of the College's research and extension program were estimated using the economic surplus approach. A sample of the college's research and extension projects was selected, and aggregate benefits for the college were evaluated. The study found substantial impacts of the college on the Commonwealth. The total impacts of the college on total output, income, Gross Domestic Product and employment on an annual are $44 million, $26 million, $28 million and 707 respectively. The sample of research projects evaluated, generated net benefits of $12 million. The aggregate benefits of the college are estimated at $48 million. The benefit-cost ratio for the college's research is 3.1.
  • Thumbnail Image
    Effects of feeding lasalocid and monensin upon mineral status of steers, and partial absorption and renal handling of minerals in sheep
    Kirk, David J. (Virginia Polytechnic Institute and State University, 1989)
    Studies were conducted to determine the effects of feeding lasalocid and monensin upon mineral status of ruminants, changes in digestive and renal physiology which bring about altered mineral status, and the effects of dietary K upon the actions of ionophores. Two 84-d grazing trials were conducted with steers fed no ionophore, 200 mg lasalocid, or 150 mg monensin. Monensin tended to increase gain of steers, but lasalocid had no effect. Feeding supplemental lasalocid and monensin altered Ca, P, Mg, Na, K, Cu, Fe and Zn status of grazing steers, but effects were not consistent. Twenty-four crossbred steers were individually fed in a 147-d finishing trial to study a possible K x monensin interaction. Steers were fed diets ad libitum containing .4% or 2.3% K, with or without 23 ppm monensin, dry basis. Feeding monensin with low K increased serum Na, Mg, inorganic P, Cu and Zn, but monensin fed with high K had no effect or decreased these serum minerals. Fifteen wethers, fitted with abomasal and ileal cannulae, were fed a basal diet alone or supplemented with 23 ppm lasalocid or monensin; Apparent absorption of Mg, K and Fe increased when ionophores were fed. Magnesium flow through the small and large intestines was decreased by lasalocid and monensin. Effects of lasalocid and monensin differed for metabolism, digestive tract flow and (or) partial absorption of Ca, P, Cu, Fe and Zn. Twelve ewe lambs were used in a renal clearance experiment. Lambs were fed a basal diet with no ionophore, 23 ppm lasalocid, or 23 ppm monensin, dry basis. Ionophores were fed starting on d 1 of the experimental period. Serial collections of blood and urine were made during d 1 and d 5 of the experimental period. Monensin reduced urine flow rate at d 1 and d 5. Feeding monensin lowered serum clearance and urinary excretion rates of Na and K at d 5. Serum clearance and urinary excretion rates of Ca were lower in sheep fed ionophores at d 1. Feeding monensin decreased serum clearance and urinary excretion rates of Cu at d 1. At d 5, urinary excretion rates of Zn were greater when lasalocid was fed, and lower when monensin was fed, compared to feeding no ionophore. These studies indicate that dietary lasalocid and monensin can alter mineral status of ruminants, although their effects may differ. The effects of ionophores may be dependent upon dietary K levels.
  • Thumbnail Image
    Effects of Vitamin E Supplementation in Late Gestation Cattle and Evaluation of Vitamin E, Cholesterol, and Phospholipid Relationships in Bovine Serum and Serum Lipoproteins
    Bass, Roger Thompson II (Virginia Tech, 1999-04-21)
    The effects of vitamin E supplementation during late gestation were evaluated in dairy or beef cattle in three experiments. Dairy cows were injected with vitamin E and selenium (Se) in one study; beef cows were offered oral vitamin E supplementation via a free-choice vitamin-mineral mix in two studies. Breed-related effects were also evaluated. Jerseys had higher blood Se and lower serum vitamin E concentrations than Holsteins at dry-off and higher blood Se concentrations than Holsteins 3-4 weeks pre-calving and at calving. Selenium supplementation increased blood Se concentrations at calving. Treatment did not affect serum vitamin E concentrations at calving or post-calving, nor blood Se concentrations post-calving. Beef cattle consuming supplemental vitamin E (treatment) had greater responses to treatment when calving in late winter than when calving in late summer. Treated multiparous cows calving in winter had increased serum and colostral vitamin E concentrations but treatment did not affect colostral or serum immunoglobulin G (IgG) concentrations of their calves. Calves from treated, multiparous cows calving in winter had increased 205-day adjusted weaning weights (AWWs). Treatment did not affect colostral vitamin E or IgG concentrations of nulliparous heifers calving in winter, nor serum vitamin E or IgG concentrations, or AWWs of their calves. Six hundred IU supplemental vitamin E/head/day did not affect serum vitamin E concentrations of dams, colostral vitamin E or IgG concentrations, serum vitamin E or IgG concentrations, or growth of calves in the summer-calving herd. Breed-related differences in vitamin E concentrations and AWW occurred in both herds. Consumption of 600-1000 IU vitamin E/cow/day (treatment) during late gestation via a free-choice vitamin-mineral mix increased vitamin E concentrations in serum and the lipoprotein fraction containing no apolipoprotein B (non-ApoB) from 1-2 weeks pre-calving to calving. Treatment group calves had higher vitamin E concentrations in serum and non-ApoB than control group calves. Treatment did not affect cholesterol or phospholipid concentrations in serum or the lipoprotein fractions of either cows or calves. Treatment increased vitamin E cholesterol (VEC) and vitamin E phospholipid (VEPL) ratios in the serum and non-ApoB of cows and calves. Various breed-related differences also occurred.
  • Thumbnail Image
    A farm-based prospective study for equine colic risk factors and risk associated events
    Tinker, Mary Kay (Virginia Tech, 1995)
    Improved definition of risk factors for equine colic is necessary to develop effective interventions to reduce colic incidence. A one-year prospective study was conducted to estimate colic incidence and to identify risk factors. Farms with greater than 20 horses were randomly selected from two adjacent counties of Virginia and Maryland. Management information was recorded by questionnaire for 31 farms with 1427 horses. Owners kept calendars to record occurrence of specified events. Colic was reported by the owner when a horse exhibited signs of abdominal pain. The incidence of colic was 10.6 colic cases per 100 horse-years, based on 104 cases per 983.5 horse-years. Twenty-five deaths occurred from all causes, the proportional mortality rate of colic was 7/25 (28%). Risk factors were analyzed by logistic regression at the farm-level and the horse-level with farm as a random effects variable. No farm-level variables were significant. Significant horse variables were: age 2-10 years, odds ratio (OR)=2.8 (95% confidence interval, 1.2-6.5); previous colic, OR=3.6(1.9-6.8); changes in concentrate feeding during the year, OR=3.6(1.6-5.4); more than one change in hay feeding during the year, OR=2.1(1.2-3.8); feeding high levels of concentrate (>2.5 kg/day dry matter, OR=4.8(1.4-16), >5 kg/day dry matter, OR=6.3(1.8-22)); and vaccination with monocytic ehrlichiosis vaccine during the study, OR=2.0(1.8-22). Feeding whole grain with or without other concentrates had less risk than diets without whole grain included. Variables related to concentrate feeding frequency or concentrate type could be substituted for the concentrate level variable. A nested analysis examined risk for the time period following an event. The odds ratio was determined for the proportion of cases with an event within 14 days prior to the colic-date, relative to the proportion of horses without colic with an event within 14 days of a date chosen at random from the observation time. Weather events were analyzed for the three days before the colic or assigned date. Foaling was analyzed for three time periods: before, 0-60 and 60-150 days post-foaling. Significant events were recent vaccination, OR=3.31(1.9-6.0); recent transport, OR=3.3(1.2-5.5); 60-150 days post-foaling, OR=5.9(1.8-13); and recent fever, OR=20(2.5-169). Snow on the day of the colic, OR=2.8(1.0-7) and humidity <50% the day before the colic OR=1.6(1.0-2.9) were marginally significant.
  • Thumbnail Image
    Lysine and methionine transport by bovine jejunal and ileal brush border membrane vesicles
    Wilson, Jonathan Wesley (Virginia Polytechnic Institute and State University, 1988)
    Purified brush border and basolateral membranes were isolated from homogenized intestinal enterocytes of Holstein steers by divalent cation precipitation followed by differential and sucrose density gradient centrifugation. Membrane marker enzymes were used to determine the effectiveness of the fractionation procedure. Alkaline phosphatase and sodium-potassium adenosine triphosphatase served as the marker enzymes for the brush border and basolateral membranes, respectively. The brush border fraction was enriched 5.1-fold over the cellular homogenate. Purification of 10.1-fold over cellular homogenate was obtained for the basolateral membrane fraction. Electronmicrographs and osmotic response data were used to confirm the vesicular nature of the membrane preparations. Brush border membrane vesicles from bovine jejunal and ileal tissue were used to evaluate lysine (LYS) and methionine (MET) transport. Total transport of LYS and MET was divided into mediated and diffusion components. Mediated uptake was further divided into sodium-dependent (Na⁺) and sodium independent (Na⁻) systems. Total LYS and MET uptake by ileal tissue tended to be higher than jejunal tissue at all concentrations evaluated but differences were significant (P<.O5) at 2.5 and 7.5 mM for LYS and 5, 12.5 and 15 mM for MET. The greater capacity of ileal tissue appeared to be due to the Na⁺ component of LYS uptake and the diffusion component of MET uptake. Methionine transporters had lower affinities and higher capacities than the corresponding LYS transporters in both ileal and jejunal tissue. Methionine transport was greater (P<.O5) than LYS transport in both ileal and jejunal tissue when initial amino acid concentration was 7.5 mM. When initial amino acid concentration was 1.25 mM, MET uptake was greater (P<.13) than LYS uptake in jejunal but not ileal tissue. The relative contribution of mediated and diffusion uptake systems to total MET and LYS uptake was found to be dependent of substrate concentration.
  • Thumbnail Image
    The Modulating Effects of Dietary Fiber and Short-Chain Fatty Acids on Enterocyte Differentiation, Maturation and Turkey Coronavirus Infection
    Tirawattanawanich, Chanin (Virginia Tech, 2001-05-17)
    In a number of mammalian species, susceptibility to enteric coronavirus infection has been shown to be age-related. This is thought to be associated with enterocyte maturation and receptor protein expression. One of the factors that can influence differentiation and maturation of enterocytes is the availability of short-chain fatty acids (SCFA) in the intestinal lumen. These compounds are by-products of the bacterial fermentation of dietary fiber and serve as the primary energy source for enterocyte metabolism. The overall objective of this dissertation was to evaluate the effects of dietary fiber and short-chain fatty acids on enterocyte differentiation, maturation, and susceptibility to coronavirus infection in turkeys. Initial work involved the development of an indirect immunoperoxidase assay (IPA) for the identification and localization of turkey coronavirus (TCV) in paraffin-embedded, acid-ethanol fixed tissue. IPA was found to be superior to indirect immunofluorescent antibody test (IFA) for this and other diagnostic purposes. To evaluate cellular differentiation and maturation, an SDS-PAGE/immunoblot technique was developed to determine relative levels of villin expression in turkey embryos. Villin is an actin-bound cytoskeletal protein known to be expressed in increasing quantities at the apical surfaces of maturing enterocytes. Villin expression level was found to increase linearly as a function of embryo age. Villin localization was performed by IPA on paraffin-embedded, acid-alcohol fixed tissue. As enterocytes (embryos) matured, villin was found to concentrate at the apical surfaces and eventually at the basolateral membranes. Experiments were also conducted to see what effect in ovo butyrate administration would have on developing embryonic enterocytes. Butyrate has been shown to enhance differentiation of non-neoplastic and neoplastic cells in culture as well as promote healing of damaged intestinal epithelium in human. Villin expression was significantly enhanced in embryos receiving 0.2 and 0.3 M butyrate 36 hours post-administration. Butyrate appeared to enhance villin expression and therefore enterocyte maturation in a dose-dependent manner. Susceptibility of turkey embryos to TCV infection as a function of age and butyrate treatment was investigated as well as epithelial localization of TCV infection in poults. The level of TCV infection of epithelium was found to increase with embryo age between 17 and 23 days. Poults showed higher levels of infection on the distal 2/3 of villi and no evidence of infection in the intestinal crypts. Butyrate administration in 21-day-old embryos followed by TCV inoculation caused a significant increase of the number of infected cells per villus. This data suggested that butyrate might be used as a means to manipulate enterocyte susceptibility to TCV infection. In the final set of experiments, the effects of fiber-fortified poult diets containing 5% cellulose or 5% guar gum on luminal SCFA levels, enterocyte maturation, and TCV infection were investigated. SCFA levels in cecal contents were determined by gas chromatography. Enterocyte maturation was assessed by the determination of villin expression on immunoblot and the severity of TCV infection was determined by IPA and lesion score. Fiber-fortified diets enhanced SCFA production and villin expression, but contrary to embryo studies, TCV infection appeared to be reduced. In general, poults performed better on the diet containing cellulose. Mechanisms regarding the roles of dietary fiber and SCFA in enterocyte differentiation, maturation, and TCV susceptibility are proposed as well as future directions for research. The in ovo and poults system used in this research may serve as models for further investigation of the influences of host and dietary factors on enteric viral infection and recovery.
  • Thumbnail Image
    Nutritional and hormonal influences on immunoglobulin absorbtion by the preruminant neonate
    Hough, Robert L. (Virginia Polytechnic Institute and State University, 1988)
    Two studies were conducted to investigate factors involved in absorption of immunoglobulins in the preruminant neonate. In the first study 26 Angus cows were fed 57% or 100% of their NRC recommended requirements for protein and energy for the last third of gestation in each of 2 years. Resulting calves were fed measured amounts of colostrum from their dam or from a cow of the reciprocal nutritional treatment group. Cows from the restricted intake treatment lost weight and body condition (P < .05). Gestation length, birth weight, calving ease, days open end weaning weight, however, were not affected by treatment. Calves born to restricted fed dame had higher serum cortisol and lower serum T₃ concentration (P < .05), but absorption of IgG was not affected. Calves fed colostrum from restricted cows did have lower serum IgG concentrations (P < 0.2); although, none of the calves were considered hypogammaglobunemic. In the second study, 2 trials were conducted to evaluate the effect of varying cortisol concentrations on Ig absorption in lambs. Treatments consisted of control (CO), high cortisol (HC), single peak of cortisol (SP) end low cortisol (LC). Lambs in trial 1 were obtained on d 136 to 138 of gestation by caesarean operation. HC and SP lambs tended to have a faster rate of Ig absorption through 24 h, but did not differ from CO lambs in serum Ig concentration by 36 h. Precocious closure to Ig absorption had occurred for LC lambs by 20 h end they had lower Ig concentrations at 36 and 48 h (P < 0.05). In trial 2, lambs were obtained on d 140 to 142 of gestation. Lambs had a shorter Ig absorptive period than trial 1 (24 vs 36 h for CO]. Premature closure for the LC lambs occurred by 16 h postpartum (P < 0.05) and they tended to have depressed Ig concentrations post 24 h.
  • Thumbnail Image
    Optimizing the Extraction of Phenolic Antioxidant Compounds from Peanut Skins
    Ballard, Tameshia Shaunt'a (Virginia Tech, 2008-07-08)
    Peanut skins are a low-value byproduct of peanut blanching operations. They have been shown to contain significant levels of phenolic compounds with demonstrated antioxidant properties. The effects of two types of extraction methods: solid-liquid extraction (SLE) and microwave-assisted extraction (MAE) on the recovery of phenolic compounds from peanut skins were investigated. Response surface methodology was used to optimize extraction conditions based on total phenolic content (TPC), ORAC (oxygen radical absorbance capacity) activity and trans-resveratrol content. The protective effect of peanut skin extracts (PSE) against hydrogen peroxide (H₂O₂)-induced oxidative stress in human brain microvascular endothelial cells (HBMEC) and the effect of PSE on lipid oxidation in commercial peanut butter were also evaluated. In the SLE method, EtOH was found to be the most efficient extraction solvent followed by MeOH, water and EA. Despite EtOH extracts having a higher TPC, samples extracted with MeOH demonstrated slightly higher ORAC activity. Resveratrol was identified in MeOH extracts but was not found in EtOH, water or EA extracts. In the MAE procedure, the maximum predicted TPC under the optimized conditions was 144 mg phenols/g skins compared to 118 mg/g with SLE. The maximum predicted ORAC activity was 2789 μmol TE/g as opposed to 2149 μmol TE/g with the SLE method. MAE was able to extract more phenolic compounds (with higher antioxidant activity) in a faster time than the SLE procedure. In addition, resveratrol was identified in PSE derived from MAE although at relatively low levels. PSE were found to have some protective effects against oxidative stress in HBMEC. Higher doses of PSE appeared to have a slightly cytotoxic effect. However, the data were highly variable which made it difficult to arrive at any definitive conclusions regarding the potential benefits of PSE in preventing oxidative damage to cells. In the PB experiment, hexanal levels over the storage period were not high enough for the samples to be considered oxidized. However, hexanal values of PB samples treated with PSE were lower than the control throughout storage, which suggests that PSE may provide some protection against oxidation of PB.
  • Thumbnail Image
    Physicochemical and Sensory Properties of Resistant Starch-Based Cereal Products and Effects on Glycemic and Oxidative Stress Responses in Hispanic Women
    Aigster, Annelisse (Virginia Tech, 2009-09-01)
    The incidence of type 2 diabetes is considered an epidemic in Western countries, and its prevalence is more common in the Hispanic population than in non-Hispanic whites. Postprandial hyperglycemia has been associated with oxidative stress (OS), thus; reducing postprandial glycemia and/or OS through dietary consumption of resistant starch (RS) may be one approach to help modulate glucose and insulin responses. The purpose of this study was twofold: 1) to evaluate the physicochemical and sensory properties of cereal food products supplemented with RS. 2) to compare the effects of a single ingestion of granola bars with high (~18 grams of RS) and low (~0 grams of RS) RS compositions on the postprandial glucose and insulin responses (n=14) and oxidative stress parameters (cellular glutathione peroxidase, F2- isoprostanes, and oxygen radical absorbance capacity) in Hispanic women (n=9). Granola bars and cereals were developed to provide 2 levels (10% and 15%) of RS; isocaloric (0% RS) control samples were prepared with readily digestible (high amylopectin) starch. Samples were stored for up to 4 weeks at 20 °C. Mean composition of the high RS granola bars was 6% protein, 15% moisture, and 18% lipid. RS levels slightly increased from 14 to 16 g/serving after 4 weeks of storage, supporting published research that RS increases with storage due to retrogradation and crystallization of amylose chains. Color became lighter as the level of RS increased (p<0.001). Granola bars containing RS were less brittle (p=0.0043) than control granola bars. Sensory results indicated granola bars/cereals were acceptable. RS-supplemented granola bars were then used for the evaluation of RS ingestion in humans. There was no difference in postprandial glucose and insulin responses after a single ingestion of a RS-supplemented (18 g) granola bar. No differences were found in the oxidative stress parameters measured. In a subgroup of subjects (n=9), a lower glucose response 30 minutes after RS consumption was found (p=0.0496). Thus, RS consumption may lower fluctuations in blood glucose, which may help manage glucose levels in individuals at risk of type 2 diabetes. Further studies of short term RS consumption are warranted to elucidate its benefits in glucose management.
  • Thumbnail Image
    Selenium supplementation and selected immune responses of beef cattle
    Swecker, William S. (Virginia Tech, 1990)
    The effect of selenium (Se) supplementation, by ad libitum salt-mineral mixture (SMM) and/or Se injection, on bovine immune response was evaluated in three experiments. Sixty weaned beef calves, with marginal blood Se (67 μg Se/1), were allotted to one of six Se treatment groups in a 70-day experiment. Antibody responses to lysozyme were lower in calves fed 20 ppm Se salt-mineral mixture (SMM) ad libitum as compared to calves fed 20 ppm Se SMM and injected with 0.1 mg Se + 1.0IU vitamin E/kg body weight, IM, or with calves ad libitum fed 80, 120, 160, or 200 ppm Se SMM. Blood Se on day 70 was higher in calves fed 80, 120, 160, or 200 ppm Se SMM than calves fed 20 ppm Se and injected with 0.1 mg Se + 1.0 IU vitamin E/kg of body weight, IM. An ad libitum 120 ppm Se SMM was compared to Se injection in 80 mid-gestation beef cows that were Se-deficient (50 μg Se/l blood). Supplementation with 120 ppm Se SMM increased blood Se in cows and calves to > 100 μg/l, increased IgG concentrations in colostrum, and increased IgG concentrations in serum of post-suckle calves. Calves from Se-adequate dams had higher Se concentrations in blood and higher average daily gains at 60 days than Se-deficient calves injected with Se at birth. An ad libitum 120 ppm Se SMM was compared to Se injection in 60 Se-deficient (41 μg Se/l blood) weaned beef calves in a 56-day experiment. Calves fed 120 ppm Se SMM and unsupplemented control calves had higher antibody responses to lysozyme than calves injected with 0.1 mg Se + 1.0 IU vitamin E/kg body weight. Blood Se concentrations increased in calves fed 120 ppm Se SMM, did not change in calves injected with 0.1 mg Se/kg body weight, and decreased in control calves. Se treatment did not affect IgA response in tears of calves.
  • Thumbnail Image
    Synthesis and Characterization of Functional Biodegradable Polyesters
    Karikari, Afia Sarpong (Virginia Tech, 2006-04-06)
    The ring opening polymerization of D,L-lactide (DLLA) using multifunctional hydroxyl-terminated initiators and catalyst/coinitiator systems based on Sn(Oct)2 afforded the preparation of star-shaped, poly(D,L-lactide)s (PDLLA)s of controlled molar mass, narrow molar mass distributions, and well-defined chain end functionality. Various modifications of star-shaped PDLLA resulted in macromolecules with tailored functionalities for biomedical applications. Star-shaped PDLLAs were modified to contain photoreactive methacrylate end groups and subsequent photo-crosslinking was performed. Photo-crosslinked networks based on methacrylated star-shaped PDLLAs exhibited thermal properties and mechanical performance that were superior to current approved clinical adhesives. In addition, the thermal and mechanical properties of the networks were strongly dependent on the composition and molar mass of the star-shaped PDLLA precursors. Tensile strengths in the range of 8-21 MPa were obtained while the Young's modulus increased from 12 to 354 MPa and were higher for networks based on urethane containing polymers. Star-shaped PDLLAs bearing complementary adenine and thymine terminal units were also prepared. The hydrogen bonding associations between complementary PDLLA macromolecules depended strongly on molar mass and hence, the concentration of multiple hydrogen bonding units. 1H NMR spectroscopy confirmed the formation of hydrogen-bonded complexes with a 1:1 optimal stoichiometry and an association constant of 84 M-1. The hydrogen-bonded complexes also exhibited significantly higher solution viscosities than non-blended polymer solutions of similar molar mass and concentration. Thermoreversible associations of PDLLA-based complementary polymers were observed in the melt phase and the melt viscosity of a blended complex was consistently an order of magnitude higher than non-functionalized star-shaped PDLLA of similar molar mass. Furthermore, melt electrospinning of the hydrogen-bonded complexes successfully resulted in fibers of significantly larger diameter (9.8 ± 2.0 µm) compared to the individual precursors (PDLLA-A = 4.0 ± 0.6 µm and PDLLA-T = 4.4 ± 1.0 µm). These results suggested that thermoreversibility, as well as the strength of the hydrogen bonding interactions between the end groups of the tailored star-shaped PDLLA-based supramolecular polymers controlled the fiber diameter in the melt electrospinning process. Highly ordered microporous honeycomb structures were developed on photo-functional star-shaped PDLLA surfaces. The pore dimensions were dependent on polymer solution concentration, polymer molar mass and relative humidity. The combination of self-organizing and cross-linking techniques resulted in free-standing, PDLLA membranes with high chemical stability as well as higher mechanical strength for further material patterning. Amikacin, an antibiotic commonly used for treating infections was successfully encapsulated in star-shaped PDLLA fibers that were electrospun from solution. Preliminary results suggested that molecular architecture influenced the encapsulation of the antibiotic and subsequent drug release profile.
  • Thumbnail Image
    Tocopherol induced angiogenesis in placental vascular network in late pregnant ewes
    Kasimanickam, Ramanathan K.; Kasimanickam, Vanmathy R.; Rodriguez, Jacobo S.; Pelzer, Kevin D.; Sponenberg, D. Phillip; Thatcher, Craig D. (2010-07-12)
    Background Tocopherols have biphasic, proangiogenic and antiangiogenic therapeutic effects. The objective of this clinical trial was to clarify tocopherol's placental angiogenic potential in late pregnant ewes following oral supplementation. Methods Eighteen pregnant ewes during late gestation were selected for this study. Ewes were given oral supplementation of 500 mg of alpha-tocopherol (aT; N = 6) or 1000 mg of gamma-tocopherol (gT; N = 7) or placebo (CON; N = 5) once daily from 107 to 137 days post breeding. Serum was obtained at weekly intervals and tissue samples were obtained at the end of supplementation to: 1) evaluate tocopherol concentrations in serum, uterus and placentome; 2) evaluate relative mRNA expressions of Vascular Endothelial Growth Factor (VEGF), Placental Growth Factor (PlGF), endothelial Nitric Oxide Synthase (eNOS) and Hypoxia Inducible Factors (HIF) in uterus, caruncle and cotyledon; 3) analyze the morphometry of the placental vascular network. Results Supplementation of aT or gT resulted in increased concentrations in serum, placentome and uterus compared to control (P < 0.05). In aT group, mRNA expressions of PlGF, eNOS and HIF-1α in cotyledon were greater than the CON group. In gT group, mRNA expressions of VEGF, eNOS, HIF-1 alpha and HIF-2 alpha in caruncle and uterus, and HIF-1α in cotyledon, were greater than the CON group. Morphometry analysis revealed increased angiogenesis in the supplemented groups. Conclusion Daily oral supplementation of aT or gT increased angiogenesis in the placental vascular network in pregnant ewes during late gestation. Increase in placental angiogenesis may provide nutrients required for the development and growth of fetus during late pregnancy.