When incubated with solutions of hydrogen peroxide, erythrocytes of stress-susceptible pigs produced more by-products of lipid peroxidation (as measured as thiobarbituric acid-reactive substances [TBARS]) than did erythrocytes from stress-resistant pigs. Using this technique, discrimination between the 2 pig types was absolute at hydrogen peroxide concentrations of 0.9 and 1.5%. This was in contrast to other methods of identifying stress-susceptible pigs, such as osmotically induced erythrocyte lysis and the determination of plasma pyruvate kinase and creatine kinase activities, for which considerable overlap of data was observed between pig types. The increased TBARS production by erythrocytes was further evidence for the existence of an antioxidant abnormality in stress-susceptible pigs. However, because there were no discernible differences in the major blood antioxidant-related values between stress-susceptible and stress-resistant pigs, the nature of the defect remains unclear. The production of TBARS by erythrocytes when incubated with hydrogen peroxide provides an improved method for identifying stress-susceptible pigs.

Objective: To compare effects of sterilization with hydrogen peroxide gas plasma (HPGP), ethylene oxide, and steam on bioadhesive properties of nylon and polyethylene lines used for stabilization of canine stifle joints. Sample: Samples of a 36.3-kg test nylon leader line, 57.8-kg test nylon fishing line, and 2-mm ultrahigh–molecular weight polyethylene (UHMWPE) were used. Procedures: In this in vitro study, samples of nylon leader line, fishing line, and UHMWPE sterilized by use of HPGP, ethylene oxide, and steam or unsterilized samples were used. Bacterial adherence on unsterilized and sterilized samples was tested with Staphylococcus epidermidis and Escherichia coli. Five samples were examined for each line type and sterilization condition, and final colony counts were obtained. Results: Bacterial adherence was significantly affected by method of sterilization for all 3 line types. For most of the samples, bacterial adherence was similar or lower when HPGP sterilization was used, compared with results for sterilization via ethylene oxide and steam, respectively. Bacterial adherence was significantly higher for UHMWPE, compared with adherence for the nylon line, regardless of the sterilization method used. Bacterial adherence was higher for nylon fishing line than for nylon leader line for S epidermidis after ethylene oxide sterilization and for E coli after HPGP and ethylene oxide sterilization. Conclusions and Clinical Relevance: Effects of HPGP sterilization on bioadhesive properties of nylon and polyethylene lines compared favorably with those for ethylene oxide and steam sterilization. Also, nylon line may be a more suitable material than UHMWPE for suture prostheses on the basis of bacterial adherence properties.

Avian peritoneal exudate macrophages, when exposed to phagocytic stimuli, produced an appreciable oxidative burst as measured by production of chemiluminescence, superoxide anion, and hydrogen peroxide. Metabolic inhibitors of the oxidative burst and scavengers of oxygen radicals clearly inhibited macrophage chemiluminescence, but had no significant effect on macrophage bactericidal activity against Escherichia coli or fungistatic activity against Candida tropicalis. Therefore, avian macrophages were capable of oxygen-independent bactericidal and fungistatic activities.

In May of 2013, porcine epidemic diarrhea virus (PEDV) was detected in swine for the first time in North America. It spread rapidly, in part due to contaminated livestock trailers. The objective of this study was to test the efficacy of an accelerated hydrogen peroxide disinfectant for inactivating PEDV in the presence of feces on metal surfaces, such as those found in livestock trailers. Three-week-old barrows were inoculated intragastrically with 5 mL of PEDV-negative feces for the negative control, 5 mL of untreated PEDV-positive feces for the positive control, and 5 mL or 10 mL of PEDV-positive feces that was subjected to treatment with a 1:16 or 1:32 concentrations of accelerated hydrogen peroxide disinfectant for a contact time of 30 min at 20°C. These pigs served as a bioassay to determine the infectivity of virus following treatment. Rectal swabs collected from the inoculated pigs on days 3 and 7 post-inoculation were tested by using PEDV-specific real-time reverse transcription polymerase chain reaction and the proportion of pigs in each group that became infected with PEDV was assessed. None of the pigs used for the bioassay in the 4 treatment groups and the negative control group became infected with PEDV, which was significantly different from the positive control group (P < 0.05) in which all pigs were infected. The results suggest that the application of the accelerated hydrogen peroxide under these conditions was sufficient to inactivate the virus in feces found on metal surfaces.

Objective—To evaluate the effect of multiple hydrogen peroxide gas plasma (HPGP) sterilizations on the rate of closure of ameroid constrictors. Sample—Thirty-six 5.0-mm ameroid constrictors. Procedures—Ameroid constrictors were randomly allocated to 6 groups. Each group underwent 1, 2, 3, 4, 5, or 6 HPGP sterilizations. Ameroid constrictors were then incubated for 35 days in canine plasma and digitally imaged at predetermined times during incubation. One individual, who was unaware of the group to which each ameroid constrictor was assigned, measured the lumen area of the constrictor on each digital image. Mean lumen area was compared among groups. Results—No ameroid constrictors were completely closed after 35 days of incubation in canine plasma. Mean lumen area after incubation did not differ among constrictors that underwent 1, 2, and 3 sterilizations. Constrictors that underwent 4 sterilizations were closed significantly more than were those that underwent 1, 2, or 3 sterilizations. Mean lumen area after incubation did not differ significantly between constrictors that underwent 5 and 6 sterilizations, although the final lumen areas for those constrictors were significantly smaller than those for constrictors that underwent 1, 2, 3, and 4 sterilizations. Conclusions and Clinical Relevance—Ameroid constrictors that underwent 5 and 6 HPGP sterilizations had a 9% to 12% decrease in lumen area, compared with that of constrictors that underwent ≤ 4 plasma sterilizations, and the use of such constrictors could increase the risk of portal hypertension and secondary acquired shunting or decrease the risk of persistent shunting.

The microbiological quality and skin appearance of poultry carcasses were determined after acetic acid and hydrogen peroxide spray. Acetic acid at 1% concentrations showed a significant effect(P0.05) effect the microbial load when compared with asample without treatment,26.33x103, 2.61x103,3.70x102,2.63x102and 27.47x103 ,2.71x103,4.41x102,2.74x102 cfu/cm2 respectively. The skin of carcasses treated with H2O2 ,was bleached and bloated.

Salmonella choleraesuis strain 38 (glycerol-positive fermentation) was repeatedly exposed to porcine neutrophils in an attempt to mimic in vivo conditions of the host immune system. After phagocytosis, viable intracellular S choleraesuis were isolated and the process was repeated at least 5 times. A fifth-passage strain-38 neutrophil-adapted clone, 38PMNa-5X, was isolated, and was compared with the parent wild-type strain 38 for changes. Strain 38PMNa-5X had increased resistance to killing by hydrogen peroxide and phagocyte killing by porcine neutrophils, as measured by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide reduction. Strain 38PMNa-5X was less invasive than the parent strain on Vero cell monolayers, and had been cured of a 50-kb plasmid. The 50-kb plasmid was marked with bacteriophage mini-Mu (kanamycin resistant) and was reinserted into strain 38PMNa-5X. Strain 38PMNa-5X was avirulent in mice, but the isolates with reinserted plasmids had intermediate resistance to neutrophil and hydrogen peroxide killing and had restored invasiveness and mouse virulence. Differences in complement sensitivity and enzymatic activity were not observed between the strains.

Canine circulating neutrophils, isolated by a blood lysing technique, were incubated with 7-S nerve growth factor (NGF), at final concentrations between 12.5 and 800 ng/ml, for 30 minutes at 37 C. Neutrophil cytosolic H2O2 production, measured by flow cytometry, after 7-S NGF incubation was not significantly different from that produced at 37 C (baseline temperature controls) alone. Phorbol myristate acetate (PMA; 100 ng/ml) stimulation of neutrophils produced cytosolic H2O2 concentrations almost 13 times that of baseline temperature control neutrophils. Preincubation of neutrophils with 7-S NGF (100 to 800 ng/ml, 30 minutes, 37 C) and subsequent stimulation by PMA resulted in augmented H2O2 production in excess of twice that of neutrophils treated with PMA alone, and almost 30 times that of baseline temperature controls.

The response of blood neutrophils to the chemotactic peptide formyl-methyl-leucyl-phenylalanine varies among species. Our results indicate that this peptide does not activate the respiratory burst of porcine neutrophils. Specifically, concentrations less than or equal to 10-6M did not cause production of either superoxide or hydrogen peroxide. Studies designed to delineate the biochemical deficit responsible for these results indicated that these cells do not express specific chemotactic peptide receptors on the external surface of the plasma membrane. Although these data do not rule out the possibility that internal stores of chemotactic peptide receptor exist, attempts to induce expression of the receptor by priming the cells with either lipopolysaccharide or calcium ionophore were unsuccessful.

When incubated with solutions of hydrogen peroxide, erythrocytes of stress-susceptible pigs produced more by-products of lipid peroxidation (as measured as thiobarbituric acid-reactive substances [TBARS]) than did erythrocytes from stress-resistant pigs. Using this technique, discrimination between the 2 pig types was absolute at hydrogen peroxide concentrations of 0.9 and 1.5%. This was in contrast to other methods of identifying stress-susceptible pigs, such as osmotically induced erythrocyte lysis and the determination of plasma pyruvate kinase and creatine kinase activities, for which considerable overlap of data was observed between pig types. The increased TBARS production by erythrocytes was further evidence for the existence of an antioxidant abnormality in stress-susceptible pigs. However, because there were no discernible differences in the major blood antioxidant-related values between stress-susceptible and stress-resistant pigs, the nature of the defect remains unclear. The production of TBARS by erythrocytes when incubated with hydrogen peroxide provides an improved method for identifying stress-susceptible pigs.