The role of various agents in chicken amyloid arthropathy.

The results of an inventory of field cases of amyloid arthropathy in chickens and of routine post-mortem recordings over a two years period are described. Studies were also performed to evaluate the amyloidogenic potential of arthrotropic bacterial species (Staphylococcus aureus, Escherichia coli and Salmonella enteritidis) isolated from chickens as well as several Enterococcus faecalis isolates compared to the amyloidogenic E. faecalis isolate (previously isolated from amyloidotic joints). As chicken anemia virus was also isolated from amyloidotic joints of field cases, it was also screened for its amyloidogenic potential. In another experiment, Mycoplasma synoviae, inactivated E. faecalis isolate 6085.94, Freund's adjuvant and an arthrotropic reovirus field isolate were also screened for amyloidogenicity by intra-articular injection. These studies showed that the ability to elicit extensive amyloid arthropathy is reserved primarily to E. faecalis, but that this property is not common to every E. faecalis isolate. Intra-articular application of complete Freund's adjuvant led to the formation of extensive joint amyloid deposits. Of the other micro-organisms studied, S. aureus, S. enteritidis and E. coli were also able to cause joint amyloidosis, but in very small amounts. Inactivated E. faecalis, chicken anemia virus and reovirus did not cause amyloid arthropathy after intra-articular inoculation. This study is consistent with results of the analyses of previous field cases and of the induction of amyloid arthropathy in chickens, suggesting a considerable role for E. faecalis in this clinical-pathological entity. Finally, strain typing by analysis of chromosomal DNA restriction endonuclease digests by pulsed-field gel electrophoresis (PFGE) of amyloidogenic, non-amyloidogenic, amyloid-associated and other E. faecalis isolates from various origins showed that all amyloidogenic and amyloid-associated E. faecalis isolates had similar restriction digests, suggesting clonal spread.

New model for chronic osteomyelitis with Staphylococcus aureus in sheep.

The purpose of this study was to develop a large animal model for chronic osteomyelitis, suitable for toxicologic research and therapeutic intervention studies. Osteomyelitis was induced in 52 healthy adult Texel sheep by injecting a sclerosing agent and a hemolytic strain of Staphylococcus aureus into the proximal tibial marrow cavity. Evaluation was done by clinical, radiologic, bacteriologic, and histologic parameters for 3 months. Clinical signs of infection consisted of localized soft tissue swelling, pain during the acute phase, and limping in all sheep. Radiologic features were moderate to extensive periosteal reaction, cortical lysis, mild to extensive new bone formation, and frequent development of sequestra limited to the proximal part of the tibia. Cultures were positive for the same strain of Staphylococcus aureus in all but one sheep. Histology showed chronic active inflammation, osteolysis, new woven bone formation, debris, clusters of bacteria, and surrounding granulation tissue. It was necessary to administer a single prophylactic dose of antibiotics 1 hour after surgery to prevent fatal sepsis. It was concluded that sheep are a suitable model for chronic osteomyelitis.

A simple technique to harvest two kidneys from one donor rat for transplantation.

Kidney transplantation in rats is a widely used and well established model in transplantation immunology and preservation research. With the conventional method, only one kidney is harvested from the donor rat. We developed a technique to harvest two kidneys separately from one donor, subsequently both kidneys were successfully implanted into two recipient rats. This technique which leads to a reduction of the number of experimental animals used is discussed in detail.

Prevention of bacteraemia by systemic ciprofloxacin treatment in rat cytomegalovirus-infected immunocompromised rats.

After total body irradiation (TBI) and subsequent rat cytomegalovirus (RCMV) infection rats developed severe neutropenia and in 90% of these animals Gram-negative bacteraemia was observed. Neutropenia was less severe (P < 0.01) and bacteraemia was not recorded (P < 0.01) in uninfected irradiated control groups. The effect of selective bowel decontamination (SBD) on the bowel flora and the incidence of bacteraemia in RCMV-infected irradiated rats was studied. Animals received ciprofloxacin 2 mg/kg/day, administered by either the oral or the subcutaneous route. After either treatment regimens the numbers of Enterobacteriaceae in the caecum and colon were reduced significantly (from 10(7) to < 10(2) g of faeces), while the total numbers of facultatively aerobic and obligatory anaerobic bacteria and the number of enterococci in the faeces was unaffected when measured 1, 3 and 7 days after the onset of treatment. The effect of ciprofloxacin treatment on the incidence of bacteraemia was recorded in RCMV-infected irradiated groups. Blood and organ cultures were taken 10 days after virus inoculation. The rate of bacteraemia decreased from 80% in untreated RCMV-infected irradiated rats affected by severe RCMV disease to < 10% in the ciprofloxacin treated groups (P < 0.01). The route of treatment did not influence these results. The uninfected irradiated and infected non-irradiated control groups showed no bacteraemia. It is concluded that symptomatic RCMV infection induces severe neutropenia, which predisposes to a high rate of Gram-negative bacteraemia, which can be prevented by eradication of the Gram-negative aerobic bacteria by means of SBD with ciprofloxacin. Systemic treatment seems to be superior for the control of Enterobacteriaceae. This may be especially useful for patients, who cannot be treated effectively by the oral route because of intestinal stasis.

Is closure of open skin wounds in rats accelerated by argon laser exposure?

The influence of linearly polarized argon laser irradiation (lambda = 488 nm and 514.5 nm) on the closure time of standardized open skin wounds was measured in rats. In two separate controlled experiments no acceleration of wound closure by laser irradiation was observed. In the first experiment the wounds were cleaned during the laser treatment period at 1 J/cm2. The second experiment at 4 J/cm2 was without mechanical wound cleaning. The contradictory results reported in the literature and possible influences of wavelength, energy density, and power density are discussed.