Browsing by Author "Glen Almond, Committee Member"

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Comparative Pharmacokinetic Approaches to Estimating the Pharmacokinetics of Water Medications in Swine
(2010-04-29) Mason, Sharon; Ronald Baynes, Committee Chair; Glen Almond, Committee Member; Jim Riviere, Committee Member; Charles Smith, Committee Member
ABSTRACT MASON, SHARON ELIZABETH. Comparative Pharmacokinetic Approaches to Estimating the Pharmacokinetics of Water Medications in Swine. (under the direction of Ronald E. Baynes). Although water medications have been used in the United States for over 40 years, the pharmacokinetics of these drugs have not been clearly discerned using compartmental pharmacokinetics techniques. No repeated dosing pharmacokinetic studies have been performed on water medications in swine. Therefore we proposed to use three proven techniques in veterinary medicine to model water medications in swine. Non-compartmental modeling, physiologically based pharmacokinetic modeling and population based pharmacokinetic modeling have provide insights in veterinary medicine over the last decade. The application of these techniques to the pharmacokinetics of water medications has never been attempted. Therefore two in vivo studies were performed collect pharmacokinetic information on these drugs and then pharmacokinetic modeling was performed to test these techniques and their application to characterize the disposition characteristics of water medications in swine production settings. In vivo experiments were performed in pigs base on the age and dosing schedules of those treated in commercial production units for tetracycline and sulfamethazine. Non-compartmental analysis techniques were initially applied to these populations. However, due to large variability and unforeseen situations, PBPK and population pharmacokinetic techniques were applied in relevant situations to these medications to provide insight into situations that traditional modeling techniques were unable to elucidate. For sulfamethazine, the use of PBPK modeling proved useful in characterizing the potentially small exposure concentrations that have been documented in the literature for over 25 years. In contrast to sulfamethazine which is chemically very stable, tetracycline has been shown to degrade over time and exposure to high temperatures and sunlight. Ancillary experiments were performed to characterize the bioactivity of tetracycline water medication as dosed in a production setting. Finally population based modeling was applied to data collected from a commercial farm settings to determine factors that may apply to all water medication administration in swine industry. This mixed effect modeling technique was able to provide increased support for the non-compartmental pharmacokinetic findings and to identify factors important to plasma concentrations of medications administered in water. PBPK and population based modeling techniques can be effectively used in modeling water medications in swine. Furthermore, they were able to determine dosing amounts and schedules as well as other factors that affect the concentration of water medications in swine.
Control of Luteolytic Sensitivity in the Porcine Corpus Luteum
(2008-04-30) Zorrilla, Leah; John Gadsby, Committee Chair; Char Farin, Committee Member; Glen Almond, Committee Member; Rob Smart, Committee Member
The porcine corpus luteum (CL) is unusual in that it does not show a luteolytic response to an exogenous dose of Prostaglandin F-2 (PGF-2 until after day 12 of an 18-21 day cycle, which is in marked contrast to other farm animal species in which luteolysis can be induced after about 6 days of the estrous cycle. The overall objective of these studies was to elucidate the mechanism by which the porcine CL acquires luteolytic sensitivity (LS=the ability to respond to PGF-2), which we hypothesized occurs between days 7 and 13 of the estrous cycle, and about which little is known. We examined the temporal patterns of expression and cellular localization of the Endothelin (ET)-1 system, Protein Kinase (PK)C isoforms, as well as genes associated with apoptosis at different stages of the estrous cycle to determine whether changes in expression correlated with the development of the acquisition of LS (i.e. between days 7-13. Additionally, we developed a cell culture system to investigate whether Tumor Necrosis Factor- (TNF-) was capable of sensitizing porcine luteal cells to PGF-2 in vitro, and thus whether it may play a role in development of LS in vivo. Our studies of expression of the ET-1 system components showed that Endothelin Converting Enzyme -1 (ECE-1) expression (protein) was increased on day 10 of the cycle, which would likely result in an increase production of active ET-1 peptide in the CL. Additionally, the results from the PKC study demonstrated that PKC  protein increased on day 13 (compared to day 7), suggesting that this particular PKC isoform may play a role in mediating the development of LS in the porcine CL. Furthermore, we showed that apoptosis-associated genes such as TNF-receptor I (TNFRI), p53 and iNOS⁄eNOS were expressed early (day 7) in the estrous cycle, suggesting the possibility that they may play also role in the acquisition of LS. Our in vitro data demonstrated that TNF- sensitized porcine luteal cells to PGF-2 in a dose dependent manner. TNF- also dose-dependently increased the expression of Endothelin Receptor A (ETA) and decreased PKC isoforms (II and ) in association with PGF-2 sensitivity. Overall, our in vivo and in vitro data are consistent with a working model in which TNF- (from infiltrating macrophages in the early CL) acts to increase ET-1 (via increased ECE-1) and ETA, resulting in increased expression of PKC , which enables luteal cells to become sensitive to the luteolytic effects of PGF-2.
Effects of FSH Administration During the Neonatal Period on Adult Sperm Concentrations in Boars
(2008-07-21) Stewart, Kara Roski; Glen Almond, Committee Member; Brenda Alston-Mills, Committee Member; Todd See, Committee Member; William Flowers, Committee Chair
This study was designed to test the effects of neonatal FSH administration on sertoli cell mitosis and adult sperm production in boars. The treatment groups received 100μg⁄kg body weight of FSH (I.M.) every other day from either day 4-22 (early) or day 22-40 (late) after birth. Volumes of FSH were corrected weekly for increases in body weight. Four boars from each treatment group were castrated on days 21, 42, 98 and 330. The testes were evaluated for GATA-4 and PCNA activities and germ cell development. Blood samples were collected weekly through 9 weeks of age and then monthly after 59 weeks of age and evaluated for testosterone, estrogen, FSH, LH and IGF-1 concentrations. Four boars from each treatment group remained intact and were used for weekly semen collection. Volume, concentration and total numbers of spermatozoa were recorded weekly and motility, mobility, and morphology analysis were performed monthly. All data was analyzed using SAS and proc GLM or proc Mixed, where appropriate. Boars in the early treatment group had an increase in testosterone concentrations at 77 weeks of age (p≤.0001). There were no differences among treatment groups in the mass of the seminiferous tubules (p=0.4055) or the number of sertoli cells per organ (p=0.7010). Only boars in the FSH treated groups had sertoli cells undergoing proliferation at day 98. The sperm concentration per ejaculate was higher for the early treatment group compared to controls or the late treatment group (p=0.06). The early treatment group also had increased numbers of primary spermatocytes as adults (p=0.0005). There were no effects of treatment on estimates of semen quality. Overall these results indicate that neonatal FSH treatment increased the length of time over which sertoli cell proliferation occurs during sexual maturation which resulted in an increase in the production of spermatozoa in adults.
Factors Affecting the Presence of Reactive Oxygen Species in the Fresh and Extended Porcine Ejaculate.
(2009-04-16) Lovercamp, Kyle W.; Sarah Ash, Committee Member; Glen Almond, Committee Member; M. Todd See, Committee Member; William L. Flowers, Committee Chair
Experiment 1 examined changes in ejaculate characteristics, semen quality and membrane lipid peroxidation over time in boars maintained under a 3 times or 1 time per week collection frequency and determined the effects of semen extender and storage time on semen quality and sperm membrane lipid peroxidation. In general, extender and storage time affected sperm quality. Sperm stored in a commercially available 3-day extender were lower for sperm quality and higher for lipid peroxidation after 7 days of storage post-collection compared to a commercially available 5-day extender. Experiment 2 used density gradient centrifugation to separate extended boar sperm into sub-populations for analysis of sperm quality, plasma membrane lipid peroxidation and sperm cell fatty acid composition over a 7 day storage period post-collection. Three ejaculates were collected and analyzed following exposure to three consecutive collection periods. The first ejaculate was collected from boars that had previously been maintained on a 1 time per week frequency. The second ejaculate was collected following a period of five collections in four days (fifth collection analyzed). The third ejaculate was a collected after a period of three days of rest following the collection of the second ejaculate. Collection period affected sperm motility over the storage period post-collection. Collection period, density layer and day of storage post-collection affected the separation patterns of sperm cells using density gradient centrifugation. These results suggest that changes in sperm separation seem to be primarily affected by collection period and day of storage post-collection and to a lesser extent, sperm motility, but not plasma membrane lipid peroxidation. Experiment 3 evaluated the effect of dietary selenium on sperm production and sperm quality. The dietary treatments were a non-supplemented negative control basal diet or the basal diet supplemented at 0.3 ppm with either organic selenium or inorganic selenium. A secondary objective was to examine changes in sperm quality over a six day storage period post-collection. Boars were fed the dietary treatments beginning at the time of weaning. Dietary treatment affected the level of selenium in the blood plasma but not the semen. Dietary treatment did not affect volume, concentration or total sperm in the ejaculate, nor did dietary treatment affect sperm motility, progressive motility, morphology, membrane lipid peroxidation and glutathione peroxidase activity over the 6 day storage period postcollection. Following density gradient centrifugation, sperm motility, progressive motility, morphology and the percentage of sperm recovered were higher in the 90% gradient compared to the 45% gradient on day 1 but not day 6 of storage post-collection. These results indicate that dietary treatment affected selenium levels in the blood, but did not affect sperm production or quality. Boar sperm cells decrease in progressive motility and buoyant density over a six day storage period which appears to affect the sperm motility, progressive motility, morphology and the percentage of sperm recovered in the high and low density layers following density gradient centrifugation, however these changes do not appear to be affected by lipid peroxidation.
Mechanisms of Prostaglandin-Stimulated Recovery of Mucosal Barrier Function in the Ischemia-Injured Porcine Intestine: Role of Intestinal Ion Transport
(2006-05-16) Moeser, Adam James; Anthony Blikslager, Committee Chair; Glen Almond, Committee Member; Jody Gookin, Committee Member; Jack Odle, Committee Member
A series of experiments were conducted to determine physiologic mechanisms of mucosal repair in the ischemia-injured intestine. The first experiment (Chapter III) investigated the contributory role of individual Cl- channels in the recovery of barrier function in ischemia-injured porcine ileum. Ischemia-injured porcine ileal mucosa was mounted in Ussing chambers. Short circuit current (Isc) and transepithelial resistance (TER) were measured in response to PGE2 and pharmacologic inhibitors of epithelial Cl- channels. Overall, results from these studies demonstrate that ClC-2-mediated intestinal Cl- secretion restores TER in ischemia-injured intestine. Chapter IV entails a study aimed at more directly investigating the role of ClC-2 in mucosal repair by evaluating mucosal repair in ischemia-injured intestinal mucosa mounted on Ussing chambers treated with the selective ClC-2 agonist, lubiprostone. Results from this suggest that activation of ClC-2 with the selective agonist, lubiprostone, stimulated elevations in TER and reduction in mannitol flux in the Ischemia-injured intestine. In Chapter V, experiments focused on the role of individual NHE isoforms in the recovery of barrier function in ischemia-injured porcine ileum. Results from this study demonstrate that inhibition of NHE2 activity, possibly via EBP50, induces recovery of barrier function in ischemic-injured intestine
Oral Vaccine Formulations Stimulate Mucosal and Systemic Antibody Responses Against Staphylococcal Enterotoxin B Using a Piglet Model.
(2010-05-25) Inskeep, Tiffany; Jack Odle, Committee Chair; Chad Stahl, Committee Member; Glen Almond, Committee Member; Kenneth Bost, Committee Member
Ovulatory and Reproductive Characteristics of Sows Treated with an Intravaginal GNRH Agonist Gel
(2005-03-01) Roski, Kara Howes; Glen Almond, Committee Member; Scott Whisnant, Committee Member; William Flowers, Committee Chair; Mitchell Hockett, Committee Member
This study was designed to test the reproductive and ovulatory characteristics of sows treated with Ovugel® (EIEICO, Radnor, PA), a gel containing a GnRH agonist (Triptorelin) administered intravaginally. The treatment groups received 100μg of GnRH agonist intravaginally in varying viscosities of the gel, .6%(n=12), .9%(n=12), 1.2%(n=12), and 1.5%(n=12) respectively. A positive control group (n=11) received saline containing 100μg of GnRH agonist while the control sows (n=12) received a vehicle of the 1.2% gel and at 96h post weaning. Jugular cannulas were placed 48 hours before administration of the treatment. Blood samples were taken every 6 hours before treatment, then every 2 hours for the first 12 hours after treatment, then every 6 hours for the next 18 hours. Estrus detection occurred every 6 hours through the entire study. Real time ultrasonography was conducted every 4 hours to determine the time of ovulation. Control sows were bred based on the onset of estrus and treatment sows were bred at +8 and +32 h after the gel was administered. All data was analyzed using SAS and the proc GLM procedure. Treatment Saline + GnRH Control 0.6% + GnRH 0.9% + GnRh 1.2% + GnRH 1.5% + GnRH Ovulation time (h) 46.5±1.2 43.8±5.4 43.8±2.0 41.2±3.3 43.5±1.8 44.5±1.5 Estrus length (h) 45.8±3.4 45.6±3.8 49.0±3.8 47±3.2 46.9±3.9 55.1±3.9 LH surge (0-30h post treatment) 7/10 5/8 7/10 9/11 8/10 8/9 Farrowing Rate 8/8 9/9 11/12 10/12 11/12 10/11 Litter Size 12.9±0.7 9±3.1.2 11±1.3 11.6±1.0 11±0.5 10.6±1.4 There were no differences in treatments in ovulation time from the onset of estrus or administration of Ovugel® (p=0.28), estrus length (p=.60), farrowing rate (p=0.80), litter size (p=0.35), or LH surge (p=0.49). However, variation associated with ovulation time was significantly reduced (p=0.01) for saline, 1.2%, and 1.5% treatments compared with controls. The duration of estrus was greater for the 1.5% gel with the triptorelin than the sows receiving only the 1.2% gel (p=0.04). The intravaginal absorption of GnRH in Ovugel® or saline along with a timed insemination program is an effective method to reduce the interval over which ovulation occurs without overtly decreasing fertility. KEY WORDS: ovulation, GnRH agonist, swine
Phenotypic and Genotypic characterization of Campylobacter isolated in swine from Conventional and Antimicrobial free farms
(2005-11-02) Thakur, Siddhartha; Glen Almond, Committee Member; Craig Altier, Committee Member; Wondwossen Gebreyes, Committee Chair; Maria Correa, Committee Member
Campylobacter is the leading cause of bacterial foodborne infections in the world. Campylobacter coli is an important species and ranks second to Campylobacter jejuni in causing clinical infection in humans in the United States. Pigs have been shown to be the major reservoir of this pathogen at the pre-harvest level in conventional swine farms where antimicrobials are used for therapeutic and growth promotion purposes. Another important facet of the swine industry is the interest in the antimicrobial free (ABF) production systems. The projected increase of 20-30% in the consumption of food products reared under antimicrobial free conditions in the United States necessitates the need to determine the status of major foodborne pathogens such as Campylobacter in swine reared under the ABF system. The purpose of this study was to determine the prevalence, antimicrobial resistance and the genetic diversity of Campylobacter isolated from swine reared in the two production systems at preharvest and during slaughter process. To better understand the epidemiology of this pathogen in the ABF system, similar comparisons were made between ABF herds reared in intensive units barns to those reared in the extensive environment. C. coli was the predominant species (99%) isolated from both the systems. High prevalence observed at the nursery level indicates that sows could act as an important source of transmission. The role played by environmental factors in transmission was highlighted by higher prevalence observed in ABF pigs reared outside with free access to soil and water. Significant reduction in prevalence was seen at the slaughter level though C. coli were isolated from post-chill samples. We recommend adding an intervention step after chilling and before packaging of the pork product. Highest frequency of resistance was seen against tetracycline and erythromycin in both the systems. We found significant association between antimicrobial resistance and the conventional production system. High frequency of pansusceptible isolates from the ABF system could be due to the absence of selective pressure of antimicrobials. Resistance against the fluoroquinolone ciprofloxacin and multidrug resistant C. coli in both systems points to the role of other unknown selective pressures and /or risk factors besides antimicrobial use. This is the first study in the US reporting ciprofloxacin resistant C. coli from swine. Ciprofloxacin resistance in C. coli is concerning as this antimicrobial is used for treating severe cases of campylobacteriosis in humans. Multilocus sequence typing was found to be a better method compared to pulsed field gel electrophoresis for genotyping C. coli based on its discriminatory power and throughput. High genetic diversity of C. coli was observed in the swine production systems as indicated by the weak clonal structure of the isolates tested. Evidence of a lineage in the ABF system will help in comparing C. coli isolates from different parts of the world. Linkage equilibrium between the housekeeping genes in isolates from the two systems could explain the high antimicrobial resistance exhibited by ABF pigs irrespective of use of antimicrobials at the farm. Overall, this study highlights the dissemination of antimicrobial resistant C. coli in swine irrespective of the production system. Resistance detected in the absence of antimicrobial selective pressure highlights the role played by unknown factors that need to be determined. We recommend studies that should be focussed on finding these sources so that effective preharvest control measures could be implemented. Finally, we recommend genotyping more isolates to better understand the epidemiology of C. coli in the swine environment.