Evaluation of 2-dodecylcyclobutanone as an irradiation dose indicator in fresh irradiated ground beef     

Gadgil P  Smith JS  Hachmeister KA  Kropf DH 《Journal of agricultural and food chemistry》2005,53(6):1890-1893

Alkylcyclobutanones (2-ACBs) are radiolytic products formed when fatty acids are irradiated. These cyclobutanones are unique irradiation byproducts and therefore may serve as indicators of irradiation exposure. As only limited information exists about 2-ACB formation in retail meat products, reliable methods that can quantify 2-ACBs and thus estimate irradiation dose in commercial meat products are desired. The cyclobutanone studied in this experiment was 2-dodecylcyclobutanone (2-DCB), which is formed from palmitic acid. The formation of 2-DCB was evaluated in fresh irradiated ground beef patties at two fat levels. Patties containing 15% and 25% fat were irradiated by electron beam at 1.0, 2.0, 3.0, and 4.5 kGy. Commercially available 1-lb irradiated ground beef chubs with different fat levels were analyzed in order to estimate dose absorbed by these samples. The 2-DCB was extracted using supercritical fluid extraction (SFE) and analyzed by gas chromatography-mass spectroscopy (GC-MS) and was detected in all the irradiated samples. The concentration of 2-DCB increased linearly with dose with R2 = 0.9646 for 25% fat samples and R2 = 0.9444 for 15% fat samples. Further, there was no significant difference in 2-DCB concentrations between the two fat levels. The estimated doses applied to the commercial samples ranged between 1.38 and 1.55 kGy, values consistent with doses normally used in the industry (1.0-2.0 kGy). Our results show that 2-DCB can be used to monitor fresh irradiated beef and approximate the absorbed dose.  相似文献   

Quantitation of carcinogenic heterocyclic aromatic amines and detection of novel heterocyclic aromatic amines in cooked meats and grill scrapings by HPLC/ESI-MS   总被引：3，自引：0，他引：3  

Turesky RJ  Taylor J  Schnackenberg L  Freeman JP  Holland RD 《Journal of agricultural and food chemistry》2005,53(8):3248-3258

A tandem solid-phase extraction method was used to isolate carcinogenic heterocyclic aromatic amines (HAAs) from cooked meats. The following 10 HAAs were identified by HPLC/ESI-MS/MS: 2-amino-9H-pyrido[2,3-b]indole (2-AalphaC), 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeAalphaC), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3-methylimidazo[4,5-f]quinoxaline (IQx), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (8-MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), 2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline (7,8-DiMeIQx), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-1,7,9-trimethylimidazo[4,5-g]quinoxaline (7,9-DiMeIgQx), and 2-amino-1-methylimidazo[4,5-b]quinoline (IQ[4,5-b]); the latter HAA has not previously been reported in cooked meats. The concentrations of these HAAs ranged from <0.03 to 15 ppb in cooked meats and poultry, to 75 ppb in cooked beef extract, and to 85 ppb in grill scrapings. The product ion scan mode was used to confirm the identities of these HAAs. Six other compounds were detected that appear to contain the N-methylimidazoquinoxaline skeleton on the basis of their product ion spectra, and these compounds are probable isomers of IQx, 8-MeIQx, and DiMeIQx. A number of known HAAs and novel HAAs of unknown genotoxic potential are formed at appreciable levels in cooked meats.  相似文献   

Assessing selenium cycling and accumulation in aquatic ecosystems   总被引：2，自引：0，他引：2  

George L. Bowie  James G. Sanders  Gerhardt F. Riedel  Cynthia C. Gilmour  Denise L. Breitburg  Gregory A. Cutter  Donald B. Porcella 《Water, air, and soil pollution》1996,90(1-2):93-104

We conducted a joint experimental research and modeling study to develop a methodology for assessing selenium (Se) toxicity in aquatic ecosystems. The first phase of the research focused on Se cycling and accumulation. In the laboratory, we measured the rates and mechanisms of accumulation, transformation, and food web transfer of the various chemical forms of Se that occur in freshwater ecosystems. Analytical developments helped define important Se forms. We investigated lower trophic levels (phytoplankton and bacteria) first before proceeding to experiments for each successive trophic component (invertebrates and fish). The lower trophic levels play critical roles in both the biogeochemical cycling and transfer of Se to upper trophic levels. The experimental research provided the scientific basis and rate parameters for a computer simulation model developed in conjunction with the experiments. The model includes components to predict the biogeochemical cycling of Se in the water column and sediments, as well as the accumulation and transformations that occur as Se moves through the food web. The modeled processes include biological uptake, transformation, excretion, and volatilization; oxidation and reduction reactions; adsorption; detrital cycling and decomposition processes; and various physical transport processes within the water body and between the water column and sediments. When applied to a Se-contaminated system (Hyco Reservoir), the model predicted Se dynamics and speciation consistent with existing measurements, and examined both the long-term fate of Se loadings and the major processes and fluxes driving its biogeochemical cycle.  相似文献   

Retrospective study of dilated cardiomyopathy in dogs     

Kimberly J. Freid  Lisa M. Freeman  John E. Rush  Suzanne M. Cunningham  Megan S. Davis  Emily T. Karlin  Vicky K. Yang 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2021,35(1):58-67

  相似文献   

Effects of conservation tillage practices on winter wheat water-use efficiency and crop yield on the Loess Plateau,China   总被引：2，自引：0，他引：2  

Ziyou Su  Jinsong Zhang  Wenliang Wu  Dianxiong Cai  Junjie Lv  Guanghui Jiang  Jian Huang  Jun Gao  Roger Hartmann  Donald Gabriels 《Agricultural Water Management》2007

In the semi-humid to arid loess plateau areas of North China, water is the limiting factor for rain-fed crop yields. Conservation tillage has been proposed to improve soil and water conservation in these areas. From 1999 to 2005, we conducted a field experiment on winter wheat (Triticum aestivum L.) to investigate the effects of conservation tillage on soil water conservation, crop yield, and water-use efficiency. The field experiment was conducted using reduced tillage (RT), no tillage with mulching (NT), subsoil tillage with mulching (ST), and conventional tillage (CT). NT and ST improved water conversation, with the average soil water storage in 0–200 cm soil depth over the six years increased 25.24 mm at the end of summer fallow periods, whereas RT soil water storage decreased 12 mm, compared to CT. At wheat planting times, the available soil water on NT and ST plots was significantly higher than those using CT and RT. The winter wheat yields were also significantly affected by the tillage methods. The average winter wheat yields over 6 years on NT or ST plots were significantly higher than that in CT or RT plots. CT and RT yields did not vary significantly between them. In each study year, NT and ST water-use efficiency (WUE) was higher than that of CT and RT. In the dry growing seasons of 1999–2000, 2004–2005 and the low-rainfall fallow season of 2002, the WUE of NT and ST was significantly higher than that of CT and RT, but did not vary significantly in the other years. For all years, CT and RT showed no WUE advantage. In relation to CT, the economic benefit of RT, NT, and ST increased 62, 1754, and 1467 yuan ha⁻¹, respectively, and the output/input ratio of conservation tillage was higher than that of CT. The overall results showed that NT and ST are the optimum tillage systems for increasing water storage and wheat yields, enhancing WUE and saving energy on the Loess Plateau.  相似文献   

MAGNETIC RESONANCE IMAGING OF BRAIN INFARCTION IN SEVEN DOGS     

William B.  Thomas  DVM  MS  Donald C.  Sorjonen  DVM  MS  Ronald O.  Scheuler  DVM  Joe N.  Kornegay  DVM  PhD 《Veterinary radiology & ultrasound》1996,37(5):345-350

Magnetic resonance imaging was performed in seven dogs with histopathologically-confirmed brain infarcts. The infarcts were non-hemorrhagic in four dogs and hemorrhagic in three dogs. Six dogs had single infarcts involving the cerebrum and one dog had multiple infarcts involving the cerebrum and brain stem. Non-hemorrhagic infarcts were typically wedge-shaped, hypointense on T1-weighted images, hyperintense on T2-weighted images, and did not enhance with gadolinium-DTPA. Hemorrhagic infarcts had mixed intensity on T1- and T2-weighted images, with variable patterns of enhancement.  相似文献   

Evaluation of age, breed, and gender as risk factors for umbilical hernia in horses of a hospital population   总被引：1，自引：0，他引：1  

D E Freeman  P A Spencer 《American journal of veterinary research》1991,52(4):637-639

Age, breed, and gender distributions of 168 horses with umbilical hernia treated at the University of Pennsylvania School of Veterinary Medicine were analyzed to determine risk factors for this disease. For the 3 breeds that constituted the largest proportion of hospital and case populations, Thoroughbred, Standardbred, and Quarter Horse, the overall ratio of females to males was 1.63. In a hospital population of the same age group, 0 to 48 months, the female to male ratio was 0.93. Compared with males, females were at significantly higher risk for umbilical hernia after adjustment for breed and age (odds ratio, 2.01; 99% confidence interval, 1.31 to 3.10; P = 0.00002). Of the 2 major breeds, Thoroughbreds were at greater risk than Standardbreds for umbilical hernia, after adjustment for gender and age (odds ratio, 1.80; 99% confidence interval, 1.10 to 2.95; P = 0.0020). The results provide information about a common congenital defect in horses that can be used for future genetic research.  相似文献   

Effect of Extenders and Osmotic Pressure on Storage of Eggs of Ornamental Common Carp Cyprinus carpio at Ambient and Refrigerated Temperatures     

Donald W.  Glenn  III Terrence R.  Tiersch 《Journal of the World Aquaculture Society》2002,33(3):254-267

The eggs of ornamental (koi) common carp Cyprinus carpi0 were stored at ambient temperature (～22–25 C) and at refrigerated temperatures (0–20 C) in extenders at different osmolalities. The treatments evaluated were dry (control), calcium‐free Hanks’balanced salt solution (C‐F HBSS), salt (NaCl), synthetic ovarian fluid (SOF), and Kurokura #2 (K2). In the first study, eggs were placed in extenders at osmolalities ranging from 130 to 450 mOsmol/kg and were fertilized after 2 h. The percentage of eyed embryos (our measure of fertilization capacity) was calculated 24 h later, and percent hatching was calculated at 60 h. Fertilization capacity of eggs suspended in C‐F HBSS (28%) or SOF (37%) was highest (P= 0.0001) at 250 mOsmol/kg, while eggs stored dry (control) had a fertilization capacity of 24%. Fertilization capacity of eggs suspended in NaCl (40%) or K2 (39%) was highest (P= 0.0001) at 200 mOsmol/kg. The percent of eyed embryos and percent hatch were found to be positively correlated (r= 0.9914). In the second study, eggs were stored in these extenders with the most effective osmolality from the previous study to evaluate percent eyed embryos and hatching over time. Samples of eggs were fertilized at every hour for 7 h. Eggs in the extenders C‐F HBSS and SOF yielded the highest (P= 0.0001) percent eyed embryos during 7 h. Percent hatch of these eggs was not significantly different (P= 0.1258) among treatments at each time interval. Eggs stored in the extenders SOF, C‐F HBSS, and NaCl had higher fertwzation capacity (P= 0.0271) at 7 h than did the dry control. Eggs were also stored at refigerated temperatures in these four extenders at the most effective osmolalities from the first study. A dry control (no extender) was also compared. The third study compared quality of eggs stored for 0, 2, 4, or 6 h in each of the extenders at 5 C or at ambient temperature (～22–25 C). Eggs suspended in C‐F HBSS had significantly higher fertilization capacity at ambient temperature over time than did eggs stored in NaCl, SOF, K2, or the dry control. Eggs suspended in C‐F HBSS and the dry control had significantly higher fertilization capacity at 5 C over time than did eggs stored in NaCl, SOF, or K2. Eggs held dry had higher hatch at ambient temperatures (P= 0.0001) and at 5 C (P = 0.0002) over time than did eggs stored in any extender. At 6 h, fertlllvltion capacity with eggs in C‐F HBSS or K2 was higher than with NaCl, SOF, or the dry control. The fourth study used C‐F HBSS (250 mOsmol/kg) as the extender to evaluate fertilizing and hatching ability during storage at temperatures 0, 5, 10, 15, 20, or 25 C. Eggs were fertilized after 0, 1, 3, 6, 9, or 12 h of storage. Eggs stored at 15 C had significantly higher fertilization capacity (P= 0.0001) than at any other temperature. Eggs stored at 15 C and 10 C had significantly higher hatch (P= 0.0001) than at any other temperature. Fertilization capacity at 12 h was significantly higher in eggs stored at 10 C (33%) or 15 C (29%) than at any other temperature. Storage of koi carp eggs in C‐F HBSS at remgerated temperatures extended fertilizing ability for as long as 12 h compared to storage in NaCl, SOF, K2, or the dry control.  相似文献   

New brine saturation technique for the extraction of light filth from rubbed sage, paprika, and corn meal: intralaboratory study.     

C C Freeman 《Journal of the Association of Official Analytical Chemists》1979,62(3):602-603

A new and widely applicable technique for the isolation of light filth from food has been developed. It includes a simple alcohol defatting followed by a brine saturation of the product by heating and cooling and a subsequent trapping of the filth elements with olive oil and tap water. The methods circumvent the use of hazardous and expensive solvents and lengthy defatting and/or pre-treatment procedures. In an intralaboratory study, recoveries of elytral squares and rodent hair fragments added to paprika, rubbed sage, and corn meal ranged from 95.8 to 100%.  相似文献   

Development and application of quantitative polymerase chain reaction assay based on the ABI 7700 system (TaqMan) for detection and quantification of Mycobacterium avium subsp. paratuberculosis.     

Sung G Kim  Sang J Shin  Richard H Jacobson  Loretta J Miller  Peter R Harpending  Susan M Stehman  Christine A Rossiter  Donald A Lein 《Journal of veterinary diagnostic investigation》2002,14(2):126-131

Numerous reports have described diagnostic methods based on the polymerase chain reaction (PCR) used to detect Mycobacterium avium subsp. paratuberculosis, the causative agent of Johne's disease. The result of conventional PCR tests has been only qualitative, either positive or negative; it does not present any quantitative information about the number of the agents in the specimen. A quantitative PCR method (IS900 TaqMan) was developed to measure the number of M. a. paratuberculosis organisms present in field and clinical samples. The sensitivity of IS900 TaqMan was 1 colony-forming unit (CFU) for M. a. paratuberculosis ATCC 19698. The specificity of the method was determined by testing 14 mycobacterial species (M. abscessus, M. asiaticum, M. avium subsp. avium, M. bovis, M. fortuitum subsp. fortuitum, M. intracellulare, M. kansasii, M. marinum, M. phlei, M. scrofulaceum, M. simiae, M. smegmatis, M. terrae, and M. ulcerans) and 9 nonmycobacterial species (Borrelia burgdorferi, Chlamydia psittaci, Ehrlichia canis, E. equi, E. risticii, Escherichia coli, E. coli O157:H7, Streptococcus equi, and S. zooepidemicus). Even at high cell numbers (10(5) CFU/reaction), most of the organisms tested negative for the IS900 insertion element except M. marinum and M. scrofulaceum. This finding for M. scrofulaceum was consistent with previous reports that several M. scrofulaceum-like isolates were positive for IS900. Those isolates had 71-79% homology with M. a. paratuberculosis in the region of IS900. When used in conjunction with the new liquid medium-based ESP culture system II for bovine clinical fecal samples, IS900 TaqMan confirmed that the ESP II-positive samples contained 10(5)-10(6) CFU/ml of M. a. paratuberculosis. All of the 222 ESP II-positive and acid-fast bacilli-positive samples tested in this study were positive by IS900 TaqMan. IS900 TaqMan was also useful in the study of growth characteristics of 3 groups of M. a. paratuberculosis strains in bovine fecal samples from 3 shedding levels (heavy, medium, and low) based on cell numbers measured by Herrold egg yolk (HEY) agar culture. When cultured in ESP medium, M. a. paratuberculosis reached 10(5)-10(6) CFU/ml within 2 weeks for heavy shedders, 3-4 weeks for medium, and 6-8 weeks for low shedders. No significant growth was observed after up to 5 weeks of incubation for some of low shedders. No or extremely slow growth characteristic of low shedders might be a possible explanation for frequent false-negative results by HEY. The detection time was dependent on the inoculum size and the growth rate of M. a. paratuberculosis. Generation times were inversely proportional to the shedding level: 1-2 days for medium and heavy shedders and >4 days for low shedders. IS900 TaqMan could be a useful tool for determining viable cell counts by measuring changes in cell numbers over the incubation period.  相似文献