Biomedical subjects

D W Morck

Publications and source records attributed to D W Morck.

At least 19 recordsLinked to original sources

PubMed2006

Temporal prevalence of antimicrobial resistance in Campylobacter spp. from beef cattle in Alberta feedlots.

Antimicrobial resistance (AMR) was temporally assessed in campylobacters isolated from beef cattle (7,738 fecal samples from 2,622 animals) in four commercial feedlots in Alberta. All calves were administered chlortetracycline and oxytetracycline in feed, and a majority of the animals (93%) were injected with long-acting oxytetracycline upon arrival at the feedlot. Fecal samples from individual animals were collected upon arrival (i.e., entry sample), 69 days (standard deviation [SD] = 3 days) after arrival (i.e., interim sample), and 189 days (SD = 33 days) after arrival (i.e., exit sample) at the feedlot. In total, 1,586 Campylobacter isolates consisting of Campylobacter coli (n = 154), Campylobacter fetus (n = 994), Campylobacter jejuni (n = 431), Campylobacter hyointestinalis (n = 4), and Campylobacter lanienae (n = 3) were recovered and characterized. The administration of antimicrobials did not decrease carriage rates of campylobacters, and minimal resistance (< or =4%) to azithromycin, ciprofloxacin, enrofloxacin, gentamicin, and meropenem was observed. In contrast, substantive increases in the prevalence of isolates resistant to tetracycline and doxycycline (56 to 89%) for C. coli, C. fetus, and C. jejuni, as well as in the number of animals (7 to 42%) from which resistant isolates were recovered, were observed during the feedlot period. Increased resistance to erythromycin (total isolates and carriages rates) was also observed in isolates of C. coli over the three isolation times. The majority of C. fetus isolates recovered were resistant to nalidixic acid, but this was independent of when they were isolated. A relatively limited number of multidrug-resistant isolates were recovered and consisted primarily of C. coli resistant to tetracyclines and erythromycin (10% of isolates). Over the course of the feedlot period, considerable increases in antimicrobial resistance were observed in C. coli, C. fetus, and C. jejuni, but with the exception of erythromycin resistance in C. coli, the administration of antimicrobial agents to beef cattle was found to have a minimal impact on resistance to macrolides and fluoroquinolones, the two classes of antimicrobials used to treat campylobacteriosis in humans. However, the widespread use of antimicrobial agents in beef production and the possible horizontal transfer of mobile genetic elements with antimicrobial resistance determinants among Campylobacter and other bacterial taxa emphasize the need to monitor AMR development in bacteria from beef cattle.

Alberta↗

PubMed2005

Effects of subtherapeutic administration of antimicrobial agents to beef cattle on the prevalence of antimicrobial resistance in Campylobacter jejuni and Campylobacter hyointestinalis.

The influence of antimicrobial agents on the development of antimicrobial resistance (AMR) in Campylobacter isolates recovered from 300 beef cattle maintained in an experimental feedlot was monitored over a 315-day period (11 sample times). Groups of calves were assigned to one of the following antimicrobial treatments: chlortetracycline and sulfamethazine (CS), chlortetracycline alone (Ct), virginiamycin, monensin, tylosin phosphate, and no antimicrobial agent (i.e., control treatment). In total, 3,283 fecal samples were processed for campylobacters over the course of the experiment. Of the 2,052 bacterial isolates recovered, 92% were Campylobacter (1,518 were Campylobacter hyointestinalis and 380 were C. jejuni). None of the antimicrobial treatments decreased the isolation frequency of C. jejuni relative to the control treatment. In contrast, C. hyointestinalis was isolated less frequently from animals treated with CS and to a lesser extent from animals treated with Ct. The majority (> or =94%) of C. jejuni isolates were sensitive to ampicillin, erythromycin, and ciprofloxacin, but more isolates with resistance to tetracycline were recovered from animals fed Ct. All of the 1,500 isolates of C. hyointestinalis examined were sensitive to ciprofloxacin. In contrast, 11%, 10%, and 1% of these isolates were resistant to tetracycline, erythromycin, and ampicillin, respectively. The number of animals from which C. hyointestinalis isolates with resistance to erythromycin and tetracycline were recovered differed among the antimicrobial treatments. Only Ct administration increased the carriage rates of erythromycin-resistant isolates of C. hyointestinalis, and the inclusion of CS in the diet increased the number of animals from which tetracycline-resistant isolates were recovered. The majority of C. hyointestinalis isolates with resistance to tetracycline were obtained from cohorts within a single pen, and most of these isolates were recovered from cattle during feeding of a forage-based diet as opposed to a grain-based diet. The findings of this study show that the subtherapeutic administration of tetracycline, alone and in combination with sulfamethazine, to feedlot cattle can select for the carriage of resistant strains of Campylobacter species. Considering the widespread use of in-feed antimicrobial agents and the high frequency of beef cattle that shed campylobacters, the development of AMR should be monitored as part of an on-going surveillance program.

Animals↗

PubMed2003

Transfer of a rifampicin-resistant Escherichia coli strain among feedlot cattle.

AIMS: To determine the incidence of transfer of a naturally occurring rifampicin-resistant strain of Escherichia coli (RREC) among cattle in a research feedlot. METHODS AND RESULTS: During three separate experiments, steers in three different pens were orally inoculated with RREC originally isolated from bovine faeces. Faecal swabs were performed on all steers in the feedlot at approximately 5 week intervals thereafter. Faecal grab samples were collected from steers in the inoculated and the immediately adjacent pens for up to 4 months. In all three experiments, the inoculated steers and penmates shed RREC within 48 h, and then shed intermittently throughout the sampling periods. Transfer of RREC to steers in an adjacent pen was confirmed only during the first experiment, but never to those in non-adjacent pens. All recovered RREC isolates were compared with the inoculated strain using multiple methods indicating that all RREC isolates were descendants of the original inoculated strain. CONCLUSIONS: Detection of the RREC strain on the pen floor and within the animal handling system, but not in the feed troughs or water bowls, suggests faecal-oral to be the primary mode of transmission among animals. SIGNIFICANCE AND IMPACT OF THE STUDY: The results suggest that in the absence of selective pressure, antibiotic-resistant bacteria may persist in cattle for a short duration but widespread transfer among cattle in a feedlot environment may be an exception rather than the norm. Modifications to feedlot management are discussed.

Animal Feed↗

PubMed2000

Diffuse lamellar keratitis related to endotoxins released from sterilizer reservoir biofilms.

OBJECTIVE: To investigate the risk factors and control mechanisms used to control the outbreak of diffuse lamellar keratitis (DLK) associated with laser in situ keratomileusis (LASIK) and examine the relationship between DLK and endotoxins released from sterilizer biofilm reservoirs. DESIGN: Clinic-based cohort and laboratory study. PARTICIPANTS: All patients undergoing LASIK at our clinic from October 7, 1998 through August 31, 1999. The case definition was a diffuse infiltrate in the interface developing within the first week after surgery. INTERVENTIONS: Biofilm control in the sterilizer, changes in sterilizer, distilled water, instruments, and irrigating fluids. MAIN OUTCOME MEASURES: The incidence of DLK after LASIK surgery. RESULTS: There were 983 evaluable patients, with three whose DLK status was not recorded. There were 52 cases of DLK. Burkholderia pickettii was isolated from the sterilizer reservoir. Potential risk factors and associations, for which there was no significant difference, included age and sex of the patients, surgeon, operating suite temperature or humidity, drapes used, saline solutions used, time of day the surgery was performed, and microkeratome use. Sterilizers 1 and 2, before biofilm control, were compared with sterilizer 3, after control. The relative risk was 9.4 (confidence limits [CL], 7.5-11.8) for sterilizer 1 versus 3 and 18. 7 (CL, 11-32) for sterilizer 2 versus 3. Three cases occurred after biofilm control, but were sporadic in nature and associated with epithelial defects. CONCLUSIONS: Clusters of DLK may be related to endotoxins released from gram-negative biofilms in sterilizer reservoirs. We experienced an outbreak of DLK affecting 52 patients and isolated B. pickettii from the sterilizer reservoir. Epidemiologic investigation showed that biofilm control in the sterilizer reservoirs was associated with a significant reduction in the development of DLK. We encourage any clinics that experience a cluster of DLK to consider microbiologic and epidemiologic investigation for the effectiveness of sterilizer biofilm control.

Adolescent↗

PubMed2000

Giardia vaccination.

Recently, a Giardia vaccine has become commercially available in the USA for prevention of clinical signs of giardiasis and reduction of cyst shedding in dogs and cats. The vaccine is based upon the current state of knowledge of Giardia antigenicity and immunology. Here, Merle Olson, Howard Ceri and Douglas Morck describe studies that led to the development of this vaccine and subsequent efficacy studies. Immunoprophylaxis and immunotherapeutic application of the vaccine are discussed.

Animals↗

PubMed2000

Is prophylactic ciprofloxacin effective in delaying biliary stent blockage?

BACKGROUND: Late stent blockage is a major complication of endoscopic stent insertion for malignant obstructive jaundice. Stents block as a result of bacterial infection and biofilm formation. We report a randomized but unblinded study using an animal model to evaluate the effect of prophylactic ciprofloxacin, which selectively suppresses gram-negative bacteria, in an attempt to prolong stent patency. METHOD: Ten adult cats underwent surgical implantation of 5F polyethylene stents through common bile duct strictures created around the choledochotomy, with the tip of the stent left in the duodenum. Five animals received intravenous ciprofloxacin perioperatively and were then maintained on oral ciprofloxacin 25 mg twice daily. Control cats were not given antibiotics. The animals were sacrificed when signs of biliary obstruction or cholangitis persisted for more than 3 days or at the end of the 16-week study period. Stents were removed and examined for patency. In addition, the stents were cultured to recover the adherent bacteria. RESULTS: All control animals developed stent blockage within 4 weeks. Two ciprofloxacin-treated cats developed stent blockage at 21 and 42 days, respectively, whereas the other 3 cats had patent stents for the entire study period. There was a significant difference between the median stent patency of 112 days for the ciprofloxacin group versus 16 days for the control group (p < 0.02). Bacteriologic cultures showed that the bile and blocked stents from the control group had predominantly gram-negative bacteria, whereas the bile and stents of the ciprofloxacin group had gram-positive and anaerobic bacteria, with an absence of gram-negative bacteria (p < 0.01). CONCLUSION: Ciprofloxacin prophylaxis eliminates gram-negative bacterial infection in bile and minimizes sludge formation and may have a potential benefit in delaying stent blockage.

Administration, Oral↗

PubMed2000

Apoptosis, oxidative metabolism and interleukin-8 production in human neutrophils exposed to azithromycin: effects of Streptococcus pneumoniae.

Pathogen virulence factors and the host inflammatory response cause tissue injury associated with respiratory tract infections. The azalide azithromycin has demonstrated efficacy in the treatment of these infections. It has been demonstrated previously that induction of polymorphonuclear leucocyte (PMN) apoptosis is associated with minimization of tissue damage and inflammation in the lung. We hypothesized that, in addition to its antibacterial effects, azithromycin may promote apoptosis. The aim of the study was to determine the effects of azithromycin on PMN apoptosis, oxidative function and interleukin-8 (IL-8) production in the presence or absence of Streptococcus pneumoniae, in comparison with penicillin, erythromycin, dexamethasone or phosphate-buffered saline. Human circulating PMNs were assessed for apoptosis (by annexin V labelling and ELISA), oxidative function (by nitroblue tetrazolium reduction) and IL-8 production (by ELISA). Azithromycin significantly induced PMN apoptosis in the absence of S. pneumoniae after 1 h (10.27% +/- 1.48%, compared with 2.19% +/- 0.42% in controls) to levels similar to those after 3 h induction with tumour necrosis factor-alpha (8. 73% +/- 1.86%). This effect was abolished in the presence of S. pneumoniae. Apoptosis in PMNs exposed to the other drugs was not significantly different from that in controls. Azithromycin did not affect PMN oxidative metabolism or IL-8 production. In summary, azithromycin-induced PMN apoptosis may be detected in the absence of any effect on PMN function, and the pro-apoptotic properties of azithromycin are inhibited in the presence of S. pneumoniae.

Apoptosis↗

PubMed2000

Tilmicosin induces apoptosis in bovine peripheral neutrophils in the presence or in the absence of Pasteurella haemolytica and promotes neutrophil phagocytosis by macrophages.

Pathogen virulence factors and inflammation are responsible for tissue injury associated with respiratory failure in bacterial pneumonia, as seen in the bovine lung infected with Pasteurella haemolytica. Tilmicosin is a macrolide antibiotic used for the treatment of bovine bacterial pneumonia. Recent evidence suggests that tilmicosin-induced neutrophil apoptosis may have anti-inflammatory effects. Using bovine leukocytes, we sought to define whether live P. haemolytica affected tilmicosin-induced neutrophil apoptosis, assessed the proapoptotic effects of tilmicosin in comparison with other drugs, and characterized its impact on phagocytic uptake of neutrophils by macrophages. Induction of apoptosis in the presence or absence of P. haemolytica was assessed by using an enzyme-linked immunosorbent assay for apoptotic nucleosomes. In addition, fluorescent annexin-V staining identified externalized phosphatidylserine in neutrophils treated with tilmicosin, penicillin, ceftiofur, oxytetracycline, or dexamethasone. Neutrophil membrane integrity was assessed by using propidium iodide and trypan blue exclusion. As phagocytic clearance of apoptotic neutrophils by macrophages contributes to the resolution of inflammation, phagocytosis of tilmicosin-treated neutrophils by esterase-positive cultured bovine macrophages was assessed with light microscopy and transmission electron microscopy. Unlike bovine neutrophils treated with penicillin, ceftiofur, oxytetracycline, or dexamethasone, neutrophils exposed to tilmicosin became apoptotic, regardless of the presence or absence of P. haemolytica. Tilmicosin-treated apoptotic neutrophils were phagocytosed at a significantly greater rate by bovine macrophages than were control neutrophils. In conclusion, tilmicosin-induced neutrophil apoptosis occurs regardless of the presence or absence of live P. haemolytica, exhibits at least some degree of drug specificity, and promotes phagocytic clearance of the dying inflammatory cells.

Animals↗

PubMed2000

Lipopolysaccharide entry in the damaged cornea and specific uptake by polymorphonuclear neutrophils.

Bacterial lipopolysaccharide (LPS) is an important agent of induction of ocular pathology following corneal injury or wearing of contaminated contact lenses. The mechanism of LPS uptake through the corneal epithelium is unclear, and the role played by inflammatory cells in this phenomenon has not been previously assessed. Fluorescein isothiocyanate-labeled LPS from Escherichia coli was deposited onto the abraded corneas of New Zealand White rabbits. Epifluorescence microscopy of living excised corneas revealed diffuse LPS staining in the epithelial and stromal layers only in the vicinity of the abrasion. In addition, specific cellular uptake of LPS was suggested by fluorescence staining of cells along the abrasion site. In a second series of experiments, an anti-CD18 polyclonal antibody was used to block infiltration of polymorphonuclear neutrophils (PMN) into the cornea. In these experiments, a diffuse distribution of fluorescent LPS was still observed along the abrasion, but the specific cellular uptake was abolished. The findings indicate that LPS enters the cornea via diffuse penetration at sites of injury and that specific cellular uptake of LPS occurs within the cornea via PMN which have migrated into the damaged tissue.

Animals↗

PubMed2000

Tilmicosin does not inhibit interleukin-8 gene expression in the bovine lung experimentally infected with Mannheimia (Pasteurella) haemolytica.

The expression of the interleukin-8 (IL-8) gene was examined by in situ hybridization in lung tissues from calves experimentally infected with Mannheimia (Pasteurella) haemolytica and treated with tilmicosin. Interleukin-8 mRNA expression was detected in alveolar areas, particularly along interlobular septa, in the lumen, and in the epithelial cells of some bronchioles. In lesional lung tissues from animals that had received tilmicosin, we found large areas with limited inflammation. There was no staining for IL-8 mRNA in these areas. In contrast, in strongly inflamed areas, the same patterns and intensities of staining for IL-8 mRNA were detected in tilmicosin- and sham-treated animals. We conclude that tilmicosin does not affect the expression of IL-8 mRNA in tissue showing microscopic signs of inflammation. Together with previous reports, this supports the view that the pro-apoptotic properties of tilmicosin on neutrophils do not compromise the host defense mechanisms required to control the infection.

Animals↗

PubMed2000

The effect of stanozolol on 15nitrogen retention in the dog.

The objective of the study was to determine the influence of either oral or intramuscular administration of stanozolol on nitrogen retention in dogs by using a non-invasive 15N-amino acid tracer technique. Ten healthy, intact, adult male sled dogs received either stanozolol tablets, 2 mg/dog PO, q12h, for 25 days (Group 1, n = 5) or an intramuscular injection of 25 mg of stanozolol on Days 7, 14, 21, and 28 (Group 2, n = 5). A 15N amino acid (5.27 mmol) was infused intravenously into each dog on Day 0 (before stanozolol treatment) and on Day 31 (after stanozolol treatment). Urine was collected by catheterization from each animal 3 times daily for 3 consecutive days. The 15N-urea enrichment in urine was determined by high-resolution mass spectrometry and the total amount of urea in the urine was determined. Both oral and injectable stanozolol resulted in significant (P < 0.05) increases in amino acid nitrogen retention compared to pretreatment values. Oral stanozolol increased nitrogen retention from 29.2 +/- 8.2% to 50.3 +/- 9.2%, while stanozolol injection increased nitrogen retention from 26.6 +/- 9.9% to 67.0 +/- 7.5%. The response to intramuscular administration was significantly greater than the response to the oral dosing regime. Stanozolol increases amino acid nitrogen retention in dogs, as has been previously observed in rats. This action of stanozolol may be beneficial in dogs under stress of surgical trauma and chronic disease.

Administration, Oral↗

PubMed1999

Duration of naturally acquired giardiosis and cryptosporidiosis in dairy calves and their association with diarrhea.

OBJECTIVE: To determine duration of infection and association of infection with diarrhea for dairy calves with naturally acquired cryptosporidiosis and giardiosis. DESIGN: Cohort study. ANIMALS: 20 Holstein calves on a single dairy farm. PROCEDURE: Fecal samples were collected 3 times/wk for the first 45 days after birth, then weekly until calves were 120 days old and examined for Giardia duodenalis cysts and Cryptosporidium parvum oocysts. Calves were monitored for diarrhea during the first 45 days after birth; during each episode of diarrhea, fecal samples were examined for parasitic, bacterial, and viral pathogens. RESULTS: All 20 calves shed Giardia cysts and Cryptosporidium oocysts at some time during the study. Mean ages at which Giardia cysts and Cryptosporidium oocysts were first detected were 31.5 and 16.3 days, respectively. Mean number of Giardia cysts in feces remained high throughout the study, whereas Cryptosporidium occysts decreased to low or undetectable numbers 2 weeks after infection. Eighteen calves had a total of 38 episodes of diarrhea during the first 45 days after birth. Giardia duodenalis was the only pathogen identified during 6 (16%) episodes, C parvum was the only pathogen identified during 9 (24%) episodes, and G duodenalis and C parvum were identified together during 10 (26%) episodes. CONCLUSIONS: Prevalences of giardiosis and cryptosporidiosis were high in these calves, and both parasites were associated with development of diarrhea. Cryptosporidium parvum was an important pathogen when calves were < 1 month old, but G duodenalis was more important when calves were older. Calves cleared C parvum infections within 2 weeks; however, G duodenalis infections became chronic in these calves.

Age Factors↗

PubMed1999

Bovine polymorphonuclear neutrophil-mediated phagocytosis and an immunoglobulin G2 protease produced by Porphyromonas levii.

Acute interdigital phlegmon (AIP) is a commonly occurring anaerobic bacterial infection in cattle. This study examined in vitro the interaction of bovine polymorphonuclear granulocytic neutrophils (PMN) from blood with bacterial species involved in AIP. Polymorphonuclear neutrophils were purified from whole bovine blood, exposed to one of the three putative etiologic agents of AIP and comparatively assessed for phagocytosis using light microscopy. Fusobacterium necrophorum and Prevotella intermedia were effectively phagocytosed by PMN, but Porphyromonas levii was phagocytosed significantly less effectively by PMN. The effect of high titre anti-P. levii bovine serum on antibody-mediated phagocytosis by PMN was also evaluated. High titre serum increased the efficiency of phagocytosis of P. levii by bovine PMN. This was independent of heat labile complement factors. Antibodies specific for P. levii were assessed for protease activity capable of cleaving bovine immunoglobulins (IgG, IgG1, IgG2, and IgM). Partially purified supernatant from broth cultures of P. levii were incubated with biotinylated immunoglobulins (Igs). Samples were taken from times 0 to 72 h and examined using SDS-PAGE followed by Western blot analysis. Streptavidin-alkaline phosphatase and NBT-BCIP were used to visualize the Igs for heavy and light chains as well as lower molecular weight fragments of these glycoproteins. Porphyromonas levii produced an immunoglobulin protease which readily cleaved bovine IgG into fragments, but did not act against IgM. Specifically, the enzyme may be a significant virulence factor as it may act to neutralize the antibodies demonstrated necessary for effective PMN-mediated phagocytosis.

Animals↗

PubMed1998

Serum immune response to Giardia duodenalis in experimentally infected lambs.

Twenty-three protozoan-free lambs were experimentally infected with Giardia duodenalis trophozoites at 6 weeks of age, while 24 controls lambs were not challenged. Weekly blood samples were taken and faecal cyst counts monitored for 11 weeks following infection. All experimentally infected lambs remained infected throughout the 11 week study period and control animals remained free of the parasite. Giardia-specific serum IgM, IgG and IgA antibody titers were determined weekly in 10 infected and 10 control lambs by enzyme-linked-immunosorbent assay (ELISA). Western blot analysis of serum immunoglobulins to proteins derived from four different Giardia isolates (S2, WB, D3 and NF) was performed. Weekly mean control IgM, IgG and IgA titers did not change throughout the study. Infected lambs showed no difference in IgM titers between weeks 0 and 11, but IgG and IgA titers of infected lambs differed from the preimmune (week 0) serum titer at weeks 5, 7, 9, 11 and weeks 5, 9 and 11 respectively. SDS polyacrylamide gel electrophoresis analysis showed homogeneity in the proteins of the four Giardia isolates. Antigenic proteins were also similar for all four isolates; however, the proteins recognized by IgM, IgG and IgA antibodies differed. The weak immune response of lambs to Giardia may account for the chronic nature of this disease in sheep.

Animals↗

PubMed1998

Comparison of ceftiofur sodium and oxytetracycline for treatment of acute interdigital phlegmon (foot rot) in feedlot cattle.

OBJECTIVE: To determine whether ceftiofur sodium would be useful for treatment of acute interdigital phlegmon (foot rot) in cattle. DESIGN: Randomized controlled trial. ANIMALS: 308 cross-bred yearling steers with clinical signs of acute interdigital phlegmon (i.e., lameness with interdigital swelling, interdigital lesions, or both). PROCEDURE: Steers were randomly assigned to 1 of 3 treatment groups: ceftiofur at a dosage of 0.1 mg/kg (0.045 mg/lb) of body weight, IM, every 24 hours; ceftiofur at a dosage of 1.0 mg/kg (0.45 mg/lb), IM, every 24 hours, and oxytetracycline at a dosage of 6.6 mg/kg (3 mg/lb), IM, every 24 hours. All animals were treated for 3 days; treatment was considered successful if animals were no longer lame on day 4. Biopsy specimens were collected prior to treatment from 5 animals in each group and submitted for anaerobic bacterial culture and histologic examination. RESULTS: Success rates for the high-dosage ceftiofur (94/129; 73%) and oxytetracycline (87/128; 68%) groups were significantly higher than that for the low-dosage ceftiofur group (5/50; 10%), but there were no significant differences between the high-dosage ceftiofur and oxytetracycline groups. Anaerobic bacteria most frequently isolated from biopsy specimens were Porphyromonas levii and Provetella intermedia. CLINICAL IMPLICATIONS: Use of ceftiofur at a dosage of 1.0 mg/kg for treatment of cattle with acute interdigital phlegmon was as effective as use of oxytetracycline at a dosage of 6.6 mg/kg. However, ceftiofur has a negligible withdrawal time and, therefore, may be a better choice for treatment of near-market weight animals.

Acute Disease↗

PubMed1998

Evaluation of autologous fat implantation in the rat urinary bladder submucosa.

OBJECTIVES: Autologous fat has been used as a bulking implant material for stress urinary incontinence. There is considerable controversy as to the ultimate fate of the grafted fat. This study was conducted to determine the fate of autogenous fat implanted into the bladder of rats. METHODS: Two groups of adult female rats were studied. In the test animals (group 1, n = 20), mesenteric adipose tissue (1 mL) was harvested and homogenized with an equal weight of sterile saline. Using a 25-gauge needle, 0.5 g of saline-fat mixture was injected into the dorsal bladder neck submucosa. Control animals (group 2, n = 12) were injected with sterile saline only. A subset of animals from each group were killed after 7, 35, 105, and 1 50 days, and the bladder and urethra were fixed. The fixed tissue was examined microscopically and photographed at each follow-up period. RESULTS: Seven days after injection of fat, there was a pronounced acute inflammatory reaction with numerous polymorphonuclear leukocytes and macrophages at the site of fat injection. There was minimal inflammatory reaction at the site of saline injection. By day 35, most of the fat had been eliminated by these phagocytes because of severe acute and chronic inflammation. By day 105, the submucosa tissue of the experimental rats had returned to normal visually and to a flat surface, lacking the appearance of a sizable "bulge" as shown at days 0 and 7. Histopathologic findings were also similar to the control rats. Inflammatory cells were no longer present by day 105. CONCLUSIONS: The implantation of homogenized, autologous fat in the rat urinary bladder submucosa causes acute and chronic inflammation and fat necrosis. The severe phagocytosis at the implant sites eliminates the vast majority of the devitalized implanted fat during the first month.

Adipose Tissue↗

PubMed1998

Serological classification and virulence determination of Dichelobacter nodosus isolated from Alberta and British Columbia sheep.

Ovine footrot is a contagious disease of sheep that occurs in temperature climates. It is caused by the strict anaerobe, Dichelobacter nodosus. Benign and virulent organisms are differentiated according to serotype and protease production. This study was conducted to identify the presence of virulent serotypes of D. nodosus in sheep flocks in Alberta and British Columbia. Dichelobacter nodosus was detected in lame sheep from 11 of 15 (73%) flocks in Alberta and in 4 of 5 (80%) British Columbia flocks. It was recovered from 57 of 107 (53%) lame sheep. In Alberta, 4 distinct serotypes were isolated from the 11 positive flocks while in British Columbia a total of 6 different serotypes were isolated. One British Columbia isolate could not be classified into existing serotypes. Of the 19 field strains tested, all but 3 were defined as virulent based upon the rapid rise in protease activity in vitro which was maintained between 3 and 5 d. The knowledge of the serotype and virulence of the D. nodosus isolated from affected animals can assist in the control and prevention of ovine footrot.

Alberta↗

PubMed1998

Anti-inflammatory benefits of tilmicosin in calves with Pasteurella haemolytica-infected lungs.

OBJECTIVES: To determine whether tilmicosin alters neutrophil infiltration or function, induces neutrophil apoptosis, and affects accumulation of leukotriene B4 (LTB4) or tumor necrosis factor-alpha (TNF-alpha) in lungs of calves experimentally infected with Pasteurella haemolytica. ANIMALS: 12 weight-ranked Holstein calves. PROCEDURE: Calves were given 25% propylene glycol vehicle (n = 5) or tilmicosin (10 mg/kg of body weight; n = 6) subcutaneously, 18 hours and 15 minutes before intratracheal infection with 2 x 10(8) P haemolytica organisms. Two unmanipulated calves served as controls in some experiments. Rectal temperatures were recorded 15 minutes before, and at 3-hour intervals after infection for 24 hours. Samples obtained from bronchoalveolar lavage performed 3 and 24 hours after infection were used to assess colonization by P haemolytica, and neutrophil infiltration. Neutrophil phagocytosis of P haemolytica, membrane leakage as determined by trypan blue exclusion, oxidative function as determined by nitro blue tetrazolium reduction, and apoptosis, using electron microscopy and DNA fragmentation ELISA, were determined. SOluble TNF-alpha and LTB4 were measured from supernatants from bronchoalveolar lavage samples, using ELISA. RESULTS: Treatment with tilmicosin resulted in significant (P < 0.05) clearance of P haemolytica and neutrophil apoptosis at 3 hours, and decreased concentration of LTB4 at 24 hours. Rectal temperatures, neutrophil infiltration, phagocytosis, oxidative functions, membrane leakage, and soluble TNF-alpha concentrations were not significantly affected by tilmicosin. CONCLUSION: Tilmicosin effectively controlled P haemolytica infection, induced neutrophil apoptosis, reduced pulmonary inflammation, and did not affect neutrophil infiltration or function. CLINICAL RELEVANCE: By inducing neutrophil apoptosis, tilmicosin prevents further amplification of inflammatory injury in P haemolytica-infected lungs.

Animals↗