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Biomedical subjects

M E Olson

Publications and source records attributed to M E Olson.

At least 109 records · Page 6Linked to original sources
PubMed1991

Bacterial invasion of the biliary system by way of the portal-venous system.

It has been suggested that bacteria in the intestine gain access into the biliary tract by entering the portal-venous blood. We have tested the hypothesis of hematogenous infection of the biliary system in cats. The animals were treated in three different groups: group A (no biliary obstruction), group B (acute biliary obstruction) and group C (chronic biliary obstruction). A mutant strain of Escherichia coli was infused into the splenic vein of cats at three different dosages (10(7), 10(5) and 10(3) with sham controls. In the unobstructed biliary system, the mutant E. coli was isolated from the bile 30 min and 90 min after the infusion of 10(7) and 10(5) E. coli, respectively. No bacteria were found in the bile with the infusion of 10(3) E. coli and in the control animals. Bile flow was significantly reduced with the infusion of bacteria. The biliary excretion of E. coli in group B was similar to that in group A. In group C, the bile output in the first hour was very high but declined rapidly. E. coli was excreted into the bile at all three dosages of infusion after 30 min. Histological sections of the liver showed that the infused bacteria entered the sinusoidal blood and that some were phagocytosed by Kupffer cells. The portal-venous blood was considered an important route of bacterial invasion into the biliary system, and the penetration of bacteria was facilitated in biliary obstruction.

Acute Disease↗
PubMed1991

Axenic isolation of viable Giardia muris trophozoites.

Large numbers of viable Giardia muris trophozoites were isolated from the duodenum of experimentally infected mice 6 days after inoculation with 1,000 G. muris cysts. A series of shaking, incubation, and washing steps in the presence of the broad-spectrum antibiotic piperacillin readily provided 4.9 +/- 1.5 x 10(5) G. muris trophozoites per mouse, free of detectable contaminant organisms. Anaerobic and microaerophilic culturing and scanning electron microscopy demonstrated axenic status and high purity of the isolates. The viability of trophozoites was 98 +/- 2%. Application of this technique should permit novel immunological and epidemiological analyses of G. muris infection and biochemical investigations of this protozoan parasite.

Animals↗
PubMed1991

Antagonism of ketamine-xylazine anesthesia in rats by administration of yohimbine, tolazoline, or 4-aminopyridine.

Antagonism of ketamine-xylazine (85 mg of ketamine/kg of body weight and 15 mg of xylazine/kg, IM) anesthesia in rats by yohimbine (YOH; 1, 5, 10, and 20 mg/kg, IP), tolazoline (TOL; 10, 20, or 50 mg/kg, IP), 4-aminopyridine (4-AP; 1 or 5 mg/kg, IP), or a combination of yohimbine and 4-aminopyridine (YOH:4-AP, 1 mg/kg:1 mg/kg or 5 mg/kg:1 mg/kg, IP) was studied. All dosages of YOH, TOL, 4-AP, and YOH:4-AP reduced the time to appearance of corneal and pedal reflexes. Only TOL was effective in reducing time to appearance of the crawl reflex and recovery time. Yohimbine, 4-AP, YOH:4-AP, and TOL were effective in reversing respiratory depression caused by ketamine-xylazine anesthesia, but anesthetic-induced hypothermia was not antagonized. When given to non-anesthetized rats, the antagonists had little influence on respiratory rate, but all antagonists caused significant (P less than 0.05) reduction in core body temperature for at least 90 minutes. When YOH was used as an anesthetic antagonist at dosage of 20 mg/kg, 20% mortality was observed and was attributable to acute respiratory arrest. The use of 4-AP and YOH:4-AP at the dosages studied induced moderate to severe muscular tremors. In conclusion, TOL at dosage of 20 mg/kg given IP, appears to be an appropriate antagonist for ketamine-xylazine anesthesia in rats.

4-Aminopyridine↗
PubMed1990

Intestinal protozoa and epithelial cell kinetics, structure and function.

Intestinal protozoa are not only common enteric pathogens in the tropics but also the high incidence of infection among immunocompromised patients in northern countries has evoked an increased interest in these parasites. Although enteric protozoa are a major cause of diarrhea and malabsorption in humans and other animals, the pathophysiology of gut disturbances caused by them remains poorly understood. Clinical signs related to enteric protozoan disease commonly involve malabsorption, diarrhea, weight loss or retarded weight gain and anorexua. Since these infections are most prevalent and most severe in the young, this may translate into considerable illness among children and significant loss to the agricultural economy where domestic animals are prone to infection. In this review we describe the effects of intestinal protozoan diseases on the structure, kinetics and function of absorptive intestinal cells and other epithelial cells, and correlate morphological injury with physiological alterations in the parasitized gut. Some of the interactions between immune responses and pathophysiology will be discussed, but in-depth discussion of intestinal immunity has recently been undertaken by other authors.

Journal Article↗
PubMed1990

Zoonotic potential of giardiasis in domestic ruminants.

This study was conducted to assess the prevalence and zoonotic potential of giardiasis in domestic ruminants. Prevalence of infection was 17.7% in sheep and 10.4% in cattle and was significantly higher in lambs and calves (35.6% and 27.7%, respectively). Naturally infected lambs released cysts intermittently for months. Giardia trophozoites from sheep had typical claw hammer-shaped median bodies and were successfully cultured in TYI-S-33 medium, and cytosolic, cytoskeletal, and membrane fractions exhibited protein profiles similar to human isolates (WB). Immunoblotting showed that sera from infected sheep recognized human Giardia, sera from patients with giardiasis recognized Giardia from sheep, and in both cases recognition involved antigenic proteins of similar molecular weight. Cyst output and clinical signs in ovine infection resemble human disease and the organisms infecting humans and ruminants are morphologically and antigenically similar. It is postulated that domestic ruminants may be a reservoir for human infection and vice versa, thus classifying giardiasis as a zooanthroponotic disease.

Alberta↗
PubMed1990

A rat model of Staphylococcus aureus chronic osteomyelitis that provides a suitable system for studying the human infection.

Chronic osteomyelitis was produced by inoculating Staphylococcus aureus into rat tibia. The infection was characterised grossly by bone deformation and histopathologically by inflammation and the presence of coccal organisms sequestered within the bone tissue. Further observations by scanning electronmicroscopy demonstrated bacteria in microcolonies surrounded by dehydrated amorphous material that was considered to be glycocalyx. Transmission electronmicroscopy, when aided by antibody stabilisation, revealed extensive glycocalyx production within the tibia. These findings indicate that the rat model of chronic S. aureus osteomyelitis mimics the human infection with respect to the sessile mode of growth of bacteria within the bone. Serum antibody levels were assayed by ELISA and immunoblotting procedures. After an initial increase, ELISA titres remained relatively stable, apparently indicating the establishment of chronic osteomyelitis, whereas in immunoblotting an increase in titre over the course of infection was observed. Whole-cell ELISA revealed less subtle differences in antibody titre than did immunoblotting with cell-wall antigen. We found that mid-range antigens, including an antigen implicated as protein A, featured prominently in the immune response in this model of infection.

Animals↗
PubMed1990

Pathogenesis of chronic bacterial prostatitis in an animal model.

A reproducible rat model of chronic bacterial prostatitis was developed using a defined bacterial pathogen (Escherichia coli) to study the pathogenesis and persistence of chronic bacterial prostatitis. The progression of inflammation and its consequences from acute to chronic prostatitis were documented with microbiological, histological, ultrastructural and immunological data. Chronic bacterial prostatitis in this model was associated with sparse glycocalix-enclosed protected bacterial microcolonies within the prostatic acini and ducts which appeared to stimulate a persistent local and systemic immunological reaction resulting in chronic inflammation of the gland. This model has many striking similarities to the natural history of human chronic bacterial prostatitis.

Animals↗
PubMed1990

Effects of murine giardiasis on growth, intestinal morphology , and disaccharidase activity.

The aim of this study was to assess the effects of Giardia muris on host growth and food intake, small intestinal morphometrics, mucosal enzyme activities, and brush border ultrastructure. Weanling mice infected with 1,000 G. muris cysts were compared to control and pair-fed sham-treated animals. Infection with G. muris resulted in decreased food intake and retarded growth. In infected animals, villus atrophy was observed in the duodenum throughout the study period and in the jejunum on days 8 and 50. On day 30, whereas jejunal architecture returned to normal in infected animals, malnourished pair-fed animals exhibited a compensatory increase in villus height. Sucrase and maltase were depressed in infected animals on days 2-24. On day 8 jejunal disaccharidases in pair-fed animals were also decreased but to a lesser extent than in infected animals. On day 24, disaccharidase values for control and infected mice were similar, whereas values in pair-fed animals were increased. On day 8, jejunal microvilli were shorter in infected animals than in control and pair-fed animals. This brush border injury was present throughout the jejunum and was also observed in pair-fed animals, but to a lesser extent. These findings suggest that G. muris retards growth in weanling mice, results in small intestinal injury, and interferes with the compensatory response to malnutrition of the infected host. Villus atrophy and brush border enzyme deficiencies associated with the disease mainly occur in the duodenum and jejunum, where trophozoites are most numerous. In infected and in pair-fed animals, the decrease in jejunal disaccharidase activities correlated with a diffuse shortening of brush border microvilli.

Animals↗
PubMed1990

A guinea pig model of bovine pneumonic pasteurellosis.

The induction of pneumonic pasteurellosis in guinea pigs (Cavia porcellus) was examined. Specific pathogen free male guinea pigs were anesthetized and a tracheostomy performed to introduce 10(5), 10(4) or 10(3) Pasteurella haemolytica-A1 into the left principal bronchus. The surgical site was closed with tissue adhesive and staples and the animals were monitored for signs of respiratory tract infection. Within 24 hours after inoculation they became depressed, anorectic, pyretic and dyspneic. Fibrinous pleuropneumonia with prominent areas of necrosis and hemorrhage was present. Pericardial effusion was a frequent finding. There was infiltration of the pleura and alveoli with degenerate heterophils and macrophages, a hyperplastic mesothelium and fibrin exudation on the pleura and within alveoli. Hemorrhage, congestion, consolidation, edema and fibrin exudation were prominent in the hilar region of the lungs. Bacterial colonies were evident in all airways. More bacteria were recovered from infected lungs than were inoculated (p less than 0.05) indicating P. haemolytica was actively multiplying in the lungs. Hematological and clinical chemistry data were consistent with fibrinous pneumonia, however, blood cultures were positive for P. haemolytica in 61% (11/18) of animals sampled. Examination of pneumonic pasteurellosis in guinea pigs may be useful in studying pathogenetic and pathological features applicable to bovine pneumonic pasteurellosis (shipping fever pneumonia).

Animals↗
PubMed1989

Tobramycin-adhesive in preventing and treating PTFE vascular graft infections.

UNLABELLED: The present study was designed to determine the effectiveness of N-butyl-2-cyanoacrylate as a vehicle to deliver antibiotics locally to contaminated vascular graft sites and to grafts with established infections. Phase I--Contaminated wound model: Sixteen dogs had a 1-cm section of infrarenal aorta replaced with a PTFE graft. Prior to placement, the graft was immersed in solutions of Escherichia coli 3 X 10(8) CFU/ml and then Staphylococcus aureus 3 X 10(8) CFU/ml. After anastomosis, 1 cc of each solution was placed directly over the graft. Eleven dogs served as controls and 5 as treatment dogs. Parenteral cefonecid was given preoperatively and daily until sacrifice. Treatment animals had the anastomoses and graft sealed with a suspension of N-butyl-2-cyanoacrylate and 1.2 g tobramycin powder (antibiotic glue, ANGL) after contamination. All dogs were reoperated on the third postoperative day. RESULTS: Eleven of 11 control dogs had positive cultures for S. aureus and 9 of 11 had positive cultures for E. coli. Seven of 11 had pseudoaneurysms, 1 exsanguinated. None of the 4 treatment dogs had positive cultures (P = 0.0002), pseudo-aneurysms (P = 0.017), or local signs of sepsis. Phase II--Infected graft model: The 10 surviving infected control dogs served as the established graft infection model. These dogs were randomized into two groups; Group 1 control (N = 5) had the graft replaced; Group 2 treatment (N = 5) had the graft replaced and ANGL treatment. Dogs were sacrificed after 2 weeks. RESULTS: Graft cultures were positive in all 4 control dogs and negative in the 4 treatment dogs (P = 0.005). One dog in each group was eliminated secondary to failure to obtain graft culture. The data show that ANGL can be effective in the prevention and treatment of prosthetic graft infection.

Administration, Topical↗
PubMed1989

Urethral replacement with tunica vaginalis: a pilot study.

A vascularized tube flap of tunica vaginalis was used to replace the penile urethra in 12 rabbits. Ten flaps were available for assessment, 2 flaps became necrotic as a result of compression of the vascular pedicle and 1 rabbit had a proximal anastomotic stricture. The healing process was satisfactory clinically and histologically in the remaining 7 flaps.

Animals↗
PubMed1989

Amdinocillin treatment of catheter-associated bacteriuria in rabbits.

The effect of the beta-lactam antibiotic, amdinocillin, on the bacterial biofilm adherent to the Foley catheter surface, the bacterial microcolonies attached to the urinary bladder mucosa, and on planktonic bacteria in the urine was studied in a rabbit model of the closed urinary catheter drainage system. Progressively increasing the dose of antibiotic in this experimental catheter-associated urinary tract infection model first eliminated the bacterial population adherent to the bladder mucosa and then the planktonic population in the urine. The bacterial biofilm on the Foley catheter could be eradicated only by the highest dose of antibiotic (400 mg/kg). Scanning electron microscopy showed a gradual deterioration of bacterial biofilm and reduction in bacterial numbers with increasing antibiotic dosages. These data suggest that antibiotics used in short-term catheterization may reduce the serious sequelae associated with catheter-related infections by clearing the potentially dangerous bladder mucosal bacterial populations and urine planktonic bacteria.

Amdinocillin↗
PubMed1989

Evaluation of the retrograde contamination guard in a bacteriologically challenged rabbit model.

We compared a newly developed closed urinary drainage system incorporating a retrograde contamination guard (RCG) with the conventional closed drainage system. The new system contains a solid bactericide (povidone iodine) pellet enclosed in a porous cartridge at the drain port of the urine collection bag. A catheterised rabbit model was used. The urine drainage bags were challenged daily for 8 days with an auxotrophically marked uropathogenic strain of Escherichia coli at the outlet tube. The bag urine was infected with the marked organism in 10 of the 11 rabbits in the control group (conventional collection bags) in 3.8 +/- 1.03 days and in only 1 of the 13 rabbits fitted with the RCG. The RCG effectively prevents contamination of the urine drainage bag and thus may play an important role in reducing the incidence of nosocomial urinary tract infections.

Animals↗
PubMed1989

Presence of bacterial glycocalyx and fimbriae on Pasteurella haemolytica in feedlot cattle with pneumonic pasteurellosis.

This investigation was conducted to determine if Pasteurella haemolytica within feedlot cattle affected by pneumonic pasteurellosis express fimbriae (pili) and bacterial glycocalyx. Bacteriological culture of pulmonary tissue from three calves with fibrinous pneumonia resulted in heavy growth of P. haemolytica. Transmission electron microscopy of the lungs showed numerous microcolonies of gram-negative bacteria with morphology typical of Pasteurella haemolytica. The cells within these microcolonies possessed bacterial glycocalyces which stained with ruthenium red. Glycocalyx-encased microcolonies were also present in specimens examined by scanning electron microscopy. Typical P. haemolytica cells were evident in a tracheal specimen and these bacteria had radial glycocalyces consistent with polysaccharide and proteinaceous material condensed on linear structures suggestive of fimbriae. The pathogenetic importance of the bacterial glycocalyx and fimbriae in shipping fever pneumonia has yet to be established but their presence in clinical cases of Pasteurella pneumonia in feedlot cattle further supports a possible role in the initiation and progression of this disease as well as bacterial resistance to antimicrobial agents.

Animals↗
PubMed1988

Gangrenous dermatitis caused by Corynebacterium ulcerans in Richardson ground squirrels.

Gangrenous dermatitis caused by Corynebacterium ulcerans developed in 63 of 350 wild Richardson ground squirrels (Spermophilus richardsonii). Six squirrels died of toxemia and/or septicemia, but 57 responded to topical and parenteral administration of antibiotics. The epizo-otic was believed to be associated with fighting; infected and carrier ground squirrels most likely transmitted the C ulcerans through bite wounds. Individuals handling ground squirrels should be cautioned that C ulcerans may produce a diphtheria-like disease in human beings.

Animals↗
PubMed1988

Colonization of n-butyl-2-cyanoacrylate tissue adhesive by Staphylococcus epidermidis.

In vitro adhesion of Staphylococcus epidermidis to cyanoacrylate tissue adhesive surfaces was investigated by employing a modified Robbins device. Bacterial colonization of n-butyl-2-cyanoacrylate tissue adhesive polymer surfaces was demonstrated by employing scanning electron microscopy, epifluorescence technique, and aerobic plate counts. The S. epidermidis was found to rapidly colonize the n-butyl-2-cyanoacrylate polymer surface producing a biofilm composed of embedded bacteria in an extensive amorphous matrix that totally occludes the material surface. The results indicate that the bacteriocidal properties of the polymer to this bacteria are weak or absent.

Enbucrilate↗
PubMed1988

The use of metronidazole, tinidazole and dimetridazole in eliminating trichomonads from laboratory mice.

Metronidazole, tinidazole and dimetridazole were administered in the drinking water for 5 days to mice experimentally infected with Tritrichomonas muris and Tetratrichomonas microta. Mice were successfully infected with T. muris and T. microta recovered from infected gerbils. The trichomonas infection was successfully eliminated in mice given a 1% sucrose solution containing 2.5 mg/ml metronidazole or tinidazole. Mice receiving 1.0 mg/ml metronidazole, 1.0 mg/ml tinidazole and 1.2, 5.0 and 10.0 mg/ml dimetridazole failed to eliminate the trichomonas organism. A reduction in water intake was only noted with mice receiving 10 mg/ml dimetridazole. In mice receiving only 1% sucrose the infection was not eliminated.

Animals↗