Graduate Student,Working on Antibiotic resistance of tylosin at Western Kentucky University and USDA bowling Green. Outstanding Graduate Student 2019. Supervisors: Eric Conte, Dr. John. H Loughrin, and Dr Agga Getahun
Increased demand for animal protein is met by increased food animal production resulting in large... more Increased demand for animal protein is met by increased food animal production resulting in large quantities of manure. Animal producers, therefore, need sustainable agricultural practices to protect environmental health. Large quantities of antimicrobials are used in commercial food animal production. Consequently, antimicrobial-resistant bacteria and the resistance genes emerge and are excreted through feces. Manure management is essential for the safe disposal of animal waste. Lagoons, with or without covers, and anaerobic digesters, with the primary purpose of methane production, and composting, with the primary purpose of producing organic fertilizer, are widely used methods of manure treatment. We reviewed manure management practices and their impact on tetracycline resistance genes. Lagoons are maintained at ambient temperatures; especially uncovered lagoons are the least effective in removing tetracycline resistance genes. However, some modifications can improve the performa...
Journal of the American Society for Mass Spectrometry, 2021
Up to 80% of the fatty acids in Staphylococcus aureus membrane lipids are branched, rather than s... more Up to 80% of the fatty acids in Staphylococcus aureus membrane lipids are branched, rather than straight-chain, fatty acids. The branched fatty acids (BCFAs) may have either an even or odd number of carbons, and the branch position may be at the penultimate carbon (iso) or the antepenultimate (anteiso) carbon of the tail. This results in two sets of isomeric fatty acid species with the same number of carbons that cannot be resolved by mass spectrometry. The isomer/isobar challenge is further complicated when the mixture of BCFAs and straight-chain fatty acids (SCFAs) are esterified into diacylated lipids such as the phosphatidylglycerol (PG) species of the S. aureus membrane. No conventional chromatographic method has been able to resolve diacylated lipids containing mixtures of SCFAs, anteiso-odd, iso-odd, and iso-even BCFAs. A major hurdle to method development in this area is the lack of relevant analytical standards for lipids containing BCFA isomers. The diversity of the S. aureus lipidome and its naturally high levels of BCFAs present an opportunity to explore the potential of resolving diacylated lipids containing BCFAs and SFCAs. Using our knowledge of lipid and fatty acid biosynthesis in S. aureus, we have used a stable-isotope-labeling strategy to develop and validate a 30 min C18 reversed-phase liquid chromatography method combined with traveling-wave ion mobility-mass spectrometry to provide resolution of diacylated lipids based on the number of BCFAs that they contain.
A sensitive, rapid and reproducible LC–MS/MS method for the determination of olmesartan (OLM), am... more A sensitive, rapid and reproducible LC–MS/MS method for the determination of olmesartan (OLM), amlodipine (ALM) and hydrochlorothiazide (HCZ) in rat plasma and urine has been developed and validated. Irbesartan (IRB) was used as an internal standard. The analytes were separated on a Waters XTerra-C18 column using gradient elution with acetonitrile and 10 mM ammonium acetate buffer (pH 3.5, adjusted with acetic acid) at a flow rate of 1.0 mL min−1. The three analytes were ionized by positive ion electrospray using multiple-reaction monitoring (MRM) mode to monitor precursor → product ion transitions m/z 447.31 → 234.97 for OLM, 408.87 → 238.18 for AML and 290.1 → 204.85 for HCZ. The specificity, matrix effect, recovery, sensitivity, linearity, accuracy, precision, and stabilities were all validated over the concentration range 0.4–100 ng mL−1 for AML, 0.2–100 ng mL−1 for OLM, 0.1–100 ng mL−1 for HCZ. The mean concentrations (Cmax) are 10.32, 587, and 3.4 for OLM, ALM, and HCZ, respectively, by the oral administration of 15 mg kg−1 of each analyte.
A sensitive, rapid and reproducible LC-MS/MS method for the determination of olmesartan (OLM), am... more A sensitive, rapid and reproducible LC-MS/MS method for the determination of olmesartan (OLM), amlodipine (ALM) and hydrochlorothiazide (HCZ) in rat plasma and urine has been developed and validated. Irbesartan (IRB) was used as an internal standard. The analytes were separated on a Waters XTerra-C 18 column using gradient elution with acetonitrile and 10 mM ammonium acetate buffer (pH 3.5, adjusted with acetic acid) at a flow rate of 1.0 mL min −1. The three analytes were ionized by positive ion electrospray using multiple-reaction monitoring (MRM) mode to monitor precursor → product ion transitions m/z 447.31 → 234.97 for OLM, 408.87 → 238.18 for AML and 290.1 → 204.85 for HCZ. The specificity, matrix effect, recovery, sensitivity, linearity, accuracy, precision, and stabilities were all validated over the concentration range 0.4-100 ng mL −1 for AML, 0.2-100 ng mL −1 for OLM, 0.1-100 ng mL −1 for HCZ. The mean concentrations (C max) are 10.32, 587, and 3.4 for OLM, ALM, and HCZ, respectively, by the oral administration of 15 mg kg −1 of each analyte.
Increased demand for animal protein is met by increased food animal production resulting in large... more Increased demand for animal protein is met by increased food animal production resulting in large quantities of manure. Animal producers, therefore, need sustainable agricultural practices to protect environmental health. Large quantities of antimicrobials are used in commercial food animal production. Consequently, antimicrobial-resistant bacteria and the resistance genes emerge and are excreted through feces. Manure management is essential for the safe disposal of animal waste. Lagoons, with or without covers, and anaerobic digesters, with the primary purpose of methane production, and composting, with the primary purpose of producing organic fertilizer, are widely used methods of manure treatment. We reviewed manure management practices and their impact on tetracycline resistance genes. Lagoons are maintained at ambient temperatures; especially uncovered lagoons are the least effective in removing tetracycline resistance genes. However, some modifications can improve the performa...
Journal of the American Society for Mass Spectrometry, 2021
Up to 80% of the fatty acids in Staphylococcus aureus membrane lipids are branched, rather than s... more Up to 80% of the fatty acids in Staphylococcus aureus membrane lipids are branched, rather than straight-chain, fatty acids. The branched fatty acids (BCFAs) may have either an even or odd number of carbons, and the branch position may be at the penultimate carbon (iso) or the antepenultimate (anteiso) carbon of the tail. This results in two sets of isomeric fatty acid species with the same number of carbons that cannot be resolved by mass spectrometry. The isomer/isobar challenge is further complicated when the mixture of BCFAs and straight-chain fatty acids (SCFAs) are esterified into diacylated lipids such as the phosphatidylglycerol (PG) species of the S. aureus membrane. No conventional chromatographic method has been able to resolve diacylated lipids containing mixtures of SCFAs, anteiso-odd, iso-odd, and iso-even BCFAs. A major hurdle to method development in this area is the lack of relevant analytical standards for lipids containing BCFA isomers. The diversity of the S. aureus lipidome and its naturally high levels of BCFAs present an opportunity to explore the potential of resolving diacylated lipids containing BCFAs and SFCAs. Using our knowledge of lipid and fatty acid biosynthesis in S. aureus, we have used a stable-isotope-labeling strategy to develop and validate a 30 min C18 reversed-phase liquid chromatography method combined with traveling-wave ion mobility-mass spectrometry to provide resolution of diacylated lipids based on the number of BCFAs that they contain.
A sensitive, rapid and reproducible LC–MS/MS method for the determination of olmesartan (OLM), am... more A sensitive, rapid and reproducible LC–MS/MS method for the determination of olmesartan (OLM), amlodipine (ALM) and hydrochlorothiazide (HCZ) in rat plasma and urine has been developed and validated. Irbesartan (IRB) was used as an internal standard. The analytes were separated on a Waters XTerra-C18 column using gradient elution with acetonitrile and 10 mM ammonium acetate buffer (pH 3.5, adjusted with acetic acid) at a flow rate of 1.0 mL min−1. The three analytes were ionized by positive ion electrospray using multiple-reaction monitoring (MRM) mode to monitor precursor → product ion transitions m/z 447.31 → 234.97 for OLM, 408.87 → 238.18 for AML and 290.1 → 204.85 for HCZ. The specificity, matrix effect, recovery, sensitivity, linearity, accuracy, precision, and stabilities were all validated over the concentration range 0.4–100 ng mL−1 for AML, 0.2–100 ng mL−1 for OLM, 0.1–100 ng mL−1 for HCZ. The mean concentrations (Cmax) are 10.32, 587, and 3.4 for OLM, ALM, and HCZ, respectively, by the oral administration of 15 mg kg−1 of each analyte.
A sensitive, rapid and reproducible LC-MS/MS method for the determination of olmesartan (OLM), am... more A sensitive, rapid and reproducible LC-MS/MS method for the determination of olmesartan (OLM), amlodipine (ALM) and hydrochlorothiazide (HCZ) in rat plasma and urine has been developed and validated. Irbesartan (IRB) was used as an internal standard. The analytes were separated on a Waters XTerra-C 18 column using gradient elution with acetonitrile and 10 mM ammonium acetate buffer (pH 3.5, adjusted with acetic acid) at a flow rate of 1.0 mL min −1. The three analytes were ionized by positive ion electrospray using multiple-reaction monitoring (MRM) mode to monitor precursor → product ion transitions m/z 447.31 → 234.97 for OLM, 408.87 → 238.18 for AML and 290.1 → 204.85 for HCZ. The specificity, matrix effect, recovery, sensitivity, linearity, accuracy, precision, and stabilities were all validated over the concentration range 0.4-100 ng mL −1 for AML, 0.2-100 ng mL −1 for OLM, 0.1-100 ng mL −1 for HCZ. The mean concentrations (C max) are 10.32, 587, and 3.4 for OLM, ALM, and HCZ, respectively, by the oral administration of 15 mg kg −1 of each analyte.
Uploads
Papers by keerthi Appala