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Bacterial Starvation Stress And Contamination Of Beef, James S. Dickson, J. F. Frank Jun 1993

Bacterial Starvation Stress And Contamination Of Beef, James S. Dickson, J. F. Frank

James S. Dickson

Salmonella typhimurium, Listeria monocytogenes, ad Escherichia coli 0157;H7 were starved by suspending washed cells in phosphate buffer for 5 days at 10, 25 or 37 degrees C. Starved bacteria were evaluated for their ability to attach to beef tissue and their sensitivity to acetic acid sanitizing. Starvation stress generally decreased the numbers of bacteria which attached to the tissue when compared to control bacterial cultures grown to late logarithmic growth phase. Starvation temperature was negatively correlated to the numbers of attached bacteria. Starvation slightly increased the sensitivity of attached S. typhimurium and L. monocytogenes cells to acetic acid, but did …


Interim Report On Data And Methods For Assessment Of 2,3,7,8-Tetrachlorodibenzo-P-Dioxin Risks To Aquatic Life And Associated Wildlife, Steven P. Bradbury, Philip M. Cook, Russell J. Erickson, Robert L. Spehar, Gerald T. Ankney Mar 1993

Interim Report On Data And Methods For Assessment Of 2,3,7,8-Tetrachlorodibenzo-P-Dioxin Risks To Aquatic Life And Associated Wildlife, Steven P. Bradbury, Philip M. Cook, Russell J. Erickson, Robert L. Spehar, Gerald T. Ankney

Steven P. Bradbury

In April, 1991 the Administrator of the U.S. Environmental Protection Agency (EPA) announced that the Agency would conduct a scientific reassessment of the risk of 2,3,7,8-tetrachlorodibenzo-p-dioxin (hereafter referred to as TCDD), and similar chemicals, to human health and the environment. Since 1985, EPA has classified TCDD, which it considers the most potent known animal carcinogen, as a probable human carcinogen. Sources of TCDD in the environment were subsequently regulated on the basis of animal cancer rates extrapolated to doses associated with human exposures. Recently, consensus has developed that the toxic effects of TCDD appear to be mediated by its binding …


Isolation Of Listeria Spp. From Feces Of Feedlot Cattle, James S. Dickson, G. R. Siragusa, E. K. Daniels Feb 1993

Isolation Of Listeria Spp. From Feces Of Feedlot Cattle, James S. Dickson, G. R. Siragusa, E. K. Daniels

James S. Dickson

Healthy feedlot beef cattle were surveyed for the presence of Listeria spp. in fecal grab samples taken over 3 months. Composite samples were made from 224 individual animals each month. Listeria monocytogenes was isolated from one composite sample (4%) from the first sampling and not from the subsequent two. Listeria innocua was found in composite samples from all three samplings at levels of 17, 9, and 35%, respectively. From the individual samples comprising the Listeria spp.—positive composites, L. monoytogenes was isolated from one sample (3%) in the second sampling but not in the first or third samplings. L. innocua was …


Heterophil Chemotaxis In Chickens With Natural Staphylococcal Infections, James R. Andreasen Jr., Claire B. Andreasen, Mohammad Anwer, Anita E. Sonn Jan 1993

Heterophil Chemotaxis In Chickens With Natural Staphylococcal Infections, James R. Andreasen Jr., Claire B. Andreasen, Mohammad Anwer, Anita E. Sonn

Claire B. Andreasen

Heterophil chemotaxis using heterophils isolated from the peripheral blood of five commercial broiler chickens naturally infected with staphylococcal bacteria was compared by the modified Boyden-chamber technique with chemotaxis of heterophils from two chickens from the same flock not infected with Staphylococcus (field controls) and from four healthy laboratory control broiler chickens. The infected chickens had gross and histologic lesions of staphylococcal tenosynovitis and osteomyelitis. Staphylococci were isolated from the lesions. Hematologic parameters and histologic lesions of infected chickens also were examined. Compared with field and laboratory controls, Staphylococcus-infected chickens had heterophilic leukocytosis. The heterophils of Staphylococcus-infected chickens had significantly lower …


Chicken Heterophil Chemotaxis Using Staphylococcus-Generated Chemoattractants, James R. Andreasen Jr., Claire B. Andreasen, Mohammad Anwer, Anita E. Sonn Jan 1993

Chicken Heterophil Chemotaxis Using Staphylococcus-Generated Chemoattractants, James R. Andreasen Jr., Claire B. Andreasen, Mohammad Anwer, Anita E. Sonn

Claire B. Andreasen

Heterophil chemotaxis, in response to chemotactic factors generated by three different strains of staphylococcal bacteria, was measured using the modified Boyden-chamber technique. Heterophils were obtained from healthy 6-to-8-week-old broiler chickens. Each bacterial strain generated factors that were chemotactic for chicken heterophils. Factors generated by two pathogenic isolates of Staphylococcus aureus, however, induced significantly greater chemotaxis in chicken heterophils than those generated by a nonpathogenic Staphylococcus isolate.


A Computer-Controlled Spray Chill Unit For Red Meat Carcasses, Maynard E. Anderson, James S. Dickson, Mark M. Hulse, Scott T. Drummond, John D. Crouse, Robert T. Marshall Jan 1993

A Computer-Controlled Spray Chill Unit For Red Meat Carcasses, Maynard E. Anderson, James S. Dickson, Mark M. Hulse, Scott T. Drummond, John D. Crouse, Robert T. Marshall

James S. Dickson

A computer controlled and operated spray chill unit which can be used in future research studies for both spray chilling and decontamination of red meat carcasses is described. The unit consists of two parts: (1) an electromechanical system, and (2) a data acquisition/control system. Design concepts for the spray chill system are (1) versatility, (2) rapid change of spray parameters, and (3) computer control of the electromechanical system. An added feature is the computer data collection system for recording information related to each carcass (pH of muscle, surface and internal tissue temperatures, and weights of each half carcass during the …


A Computer Controlled Spray Chill Unit For Red Meat Carcasses, Maynard E. Anderson, James S. Dickson, Mark M. Hulse, Scott T. Drummond, John D. Crouse, Robert T. Marshall Jan 1993

A Computer Controlled Spray Chill Unit For Red Meat Carcasses, Maynard E. Anderson, James S. Dickson, Mark M. Hulse, Scott T. Drummond, John D. Crouse, Robert T. Marshall

James S. Dickson

A computer controlled and operated spray chill unit which can be used in future research studies for both spray chilling and decontamination of red meat carcasses is described. The unit consists of two parts: (1) an electromechanical system, and (2) a data acquisition/control system. Design concepts for the spray chill system are (1) versatility, (2) rapid change of spray parameters, and (3) computer control of the electromechanical system. An added feature is the computer data collection system for recording information related to each carcass (pH of muscle, surface and internal tissue temperatures, and weights of each half carcass during the …