Biomedical subjects

M E Olson

Publications and source records attributed to M E Olson.

At least 91 records · Page 5Linked to original sources

PubMed1993

Adaptation of the small intestine in desert-dwelling animals: morphology, ultrastructure and electrolyte transport in the jejunum of rabbits, rats, gerbils and sand rats.

1. The aim of this study was to characterize adaptive alterations of the small intestine in desert-dwelling animals by comparing jejunal morphology, ultrastructure and function in mammalian species with or without desert habitat origins. 2. Crypt-villus architecture, brush border surface area, and electrolyte transport were measured and compared in the jejunum of rabbits (Oryctolagus cuniculus), rats (Rattus rattus), gerbils (Meriones unguiculatus) and sand rats (Psammomys obesus). 3. In addition, transport of 3-0-methyl-D-glucose was compared in rats, rabbits and gerbils. 4. Gerbils and sand rats had significantly longer microvilli and villi (P < 0.01), increased brush border surface area (P < 0.01), and greater absorption of Na+ and Cl- (P < 0.05) than rabbits and rats. 5. Absorption of 3-0-methyl-D-glucose was also significantly (P < 0.05) greater in gerbils than in rabbits or rats. 6. The findings demonstrate enhanced small intestinal absorption of electrolytes and nutrients in desert-dwelling animals. 7. This increase was associated with an enlarged mucosal absorptive surface area. 8. The findings suggest that intestinal mucosal adaptation allows desert-dwelling animals to compensate for the limited availability of water and nutrients in an arid environment.

3-O-Methylglucose↗

PubMed1993

A porcine model of Staphylococcus epidermidis catheter-associated infection.

The suitability of using catheterized, partially nephrectomized (uremic) pigs to study catheter-associated infection in peritoneal dialysis was investigated. In some pigs, an inoculum of 10(9) cfu of Staphylococcus epidermidis ATCC 35984 was deposited around the catheter exit site and the organism was allowed to colonize over 21 days. The strain was recoverable from tissues and catheter samples at various locations along the catheter tract from inoculated pigs at postmortem examination. Uninoculated control catheters were colonized to a significantly lesser degree and by various other staphylococcal species. Immune response by inoculated pigs toward catheter-associated bacteria was indicated by a significant increase in serum antistaphylococcal IgG concentration and an increased percentage of peripheral polymorphonuclear leukocytes. Uremia had no significant effect on serologic response. Immunoblotting against S. epidermidis lysostaphin-extracted proteins showed that although incubation with inoculated group antisera produced more intense banding and reacted to a wider range of protein than did antisera from uninoculated controls, common antigenic proteins among the groups were found.

Animals↗

PubMed1993

Waterborne Giardia cysts and Cryptosporidium oocysts in the Yukon, Canada.

Several outbreaks of waterborne giardiasis have occurred in southern Canada, but nothing has been reported from the Canadian North. The objective of this study was to collect information relevant to waterborne giardiasis and cryptosporidiosis in the Yukon including epidemiological data and analyses of water, sewage, and animal fecal samples. Remote, pristine water samples were found to be contaminated with Giardia cysts (7 of 22 or 32%) but not with Cryptosporidium oocysts. Giardia cysts were found in 21% (13 of 61) of animal scats, but no Cryptosporidium oocysts were observed (small sample size). Whitehorse's drinking water was episodically contaminated with Giardia cysts (7 of 42 or 17%) and Cryptosporidium oocysts (2 of 42 or 5%). Neither were found in Dawson City's water supply. The only water treatment in the Yukon is chlorination, but contact times and free chlorine residuals are often too low to provide adequate protection by disinfection. Raw sewage samples from the five largest population centers in the Yukon contained 26 to 3,022 Giardia cysts and 0 to 74 Cryptosporidium oocysts per liter. Treated sewage from Whitehorse contained fewer Giardia cysts but more Cryptosporidium oocysts on average. Both were detected in Lake Laberge, downstream of Whitehorse, which has a history of fecal coliform contamination. Daily monitoring of raw sewage from the suburbs of Whitehorse showed a summertime peak of Giardia cysts and occasional Cryptosporidium oocysts after springtime contamination of drinking water. Despite this evidence, epidemiological data for the Yukon showed an endemic infection rate of only 0.1% for giardiasis (cryptosporidiosis is not notifiable).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Effect of growth conditions on expression and antigenicity of Staphylococcus epidermidis RP62A cell envelope proteins.

Staphylococcus epidermidis RP62A (ATCC 35984) was grown in tryptic soy broth (TSB), iron-depleted TSB (TSB-Fe), iron-reconstituted TSB-Fe (TSB+Fe), a chemically defined medium, and fetal calf serum (FCS) and on silastic disks in chambers that were sutured to the pig peritoneal wall. Bacterial cell wall proteins were extracted by digestion with recombinant lysostaphin, separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and detected by silver staining. Cell wall proteins from TSB-, chemically defined medium-, or FCS-grown cells had a complex profile of greater than 25 protein bands spanning the full molecular mass range. By contrast, a digest obtained from in vivo-grown cells had only five major proteins of 40 kDa or greater. Proteins of 130 and 106 kDa were present in the cell envelopes of TSB-Fe- and in vivo-grown cells but not in those grown in TSB or TSB+Fe. A 43-kDa protein expressed by in vitro-grown cells and 52- and 96-kDa proteins expressed by in vivo-grown cells reacted with antisera from pigs with the chamber implants and from catheterized, paracatheter-inoculated pigs but not with hyperimmune sera from pigs immunized with TSB-grown cells. The data indicate that S. epidermidis, growing under in vivo conditions, expresses antigens distinct from those that are grown in vitro.

Animals↗

PubMed1992

Flavobacterium indologenes infection in leopard frogs.

An investigation of an epidemic of infectious disease in a frog (Rana pipiens) colony was conducted. Six of 40 frogs in a continuous (once through) water flow housing system had weight loss, swollen abdomen, corneal edema, uveitis, subcutaneous edema, petechial hemorrhage, incoordination, and respiratory distress. The frogs had lesions consistent with bacterial septicemia. A gram-negative, nonfermenting bacillus, Flavobacterium indologenes (Flavobacterium sp biovar IIb), was isolated in pure culture from tissues and blood. The clinical isolate was used to inoculate healthy frogs sc. An isolate identical to the one isolated from the sick frogs was recovered from tissues and blood of the inoculated frogs. Inoculation of the housing water in a nonflow-through system did not result in disease, despite proliferation of the Flavobacterium spp in the water; therefore, it is likely that establishment of infection requires the presence of the organism in sufficient numbers and a portal of entry into the body.

Animals↗

PubMed1992

Pathophysiology of small intestinal malabsorption in gerbils infected with Giardia lamblia.

Mongolian gerbils were infected with a human pathogenic Giardia lamblia strain and compared with sham-treated control animals 6 days after inoculation. Infection resulted in crypt hyperplasia associated with an increased enterocyte migration rate. Villus height was decreased in the duodenum, unchanged in the jejunum, and increased in the ileum of infected animals. Epithelial microvilli were markedly shortened, and brush border surface area decreased in the jejunum and ileum of infected animals. Thymidine kinase activity was increased in isolated duodenal villus enterocytes but did not differ in the jejunum and ileum. In vitro and in vivo experiments showed that the infection resulted in decreased jejunal glucose-stimulated electrolyte, water, and 3-O-methyl-D-glucose absorption, whereas in the ileum in vitro electrolyte and 3-O-methyl-D-glucose absorption was similar in infected and control animals. Thus, in the jejunum infection causes electrolyte, solute, and fluid malabsorption associated with decreased brush border surface area. The results indicate that the diarrhea associated with giardiasis is caused by malabsorption rather than active secretion.

Animals↗

PubMed1992

Evaluation of strategies for central venous catheter replacement.

OBJECTIVES: To assess the consequences of leaving a bacterially colonized central venous catheter in place and to compare the effects of three catheter replacement strategies for catheter repair control in an animal model. DESIGN: Prospective study. SETTING: Laboratory and animal facility of a large university. SUBJECTS: Eighteen healthy, female, adult sheep. INTERVENTIONS: Radiopaque-siliconized elastomer central venous catheters were inserted into the jugular veins and colonized with either Escherichia coli or Staphylococcus epidermidis. After 7 days of infection, the catheters were either: a) exchanged using a guidewire; b) removed and replaced with a new catheter in a new jugular vein site after a 48-hr interval; or c) exchanged using a guidewire and antibiotics (tobramycin, cephaloridine) injected into the catheter. Animals were euthanized 7 days after insertion of the new catheter. Quantitative microbiology was performed on blood samples collected daily from the catheters and a peripheral vein, as well as from catheters and tissue recovered from the sheep at the time of autopsy. MEASUREMENTS AND MAIN RESULT: When catheters were changed using a guidewire, they became colonized by bacteria within 48 hrs, and the sheep had embolic pneumonia and vegetative endocarditis at autopsy. Similar consequences were observed when antibiotics were administered into the catheter lumen. If colonized catheters were removed and a new catheter was inserted after a 48-hr interval, recolonization, pneumonia, and endocarditis were not observed. CONCLUSIONS: Replacement of a biofilm-colonized central venous catheter over a guidewire is associated with rapid colonization of the replacement catheter and production of detached, slime-enclosed, antibiotic-resistant aggregates that colonize other catheters or initiate endocarditis or pneumonia by dissemination in the bloodstream.

Animals↗

PubMed1992

Mechanism of persistent infection associated with peritoneal implants.

The ability of rabbits to clear an intraperitoneal injection of Pseudomonas aeruginosa in the presence or absence of a surgically implanted peritoneal device was investigated. Sham-operated rabbits without an implant eliminated a P. aeruginosa challenge of 5 x 10(6) cfu/ml; lavage fluid and peritoneal tissues became culture-negative within 96 h. However, peritonitis developed in rabbits that were given the same number of bacteria in the presence of an implant; high bacterial counts were recovered from the lavage fluid and the device itself. Scanning and transmission electronmicroscopy revealed bacterial biofilms on the surface of the device. Insertion of pre-colonised devices demonstrated a rapid multiplication of sessile organisms within the resulting bacterial biofilm. Counts reached a plateau of about 1 x 10(7) cfu/cm2 of Silastic by day 16 and fluctuated around this level until the end of the study. Pre-immunisation with formalin-killed whole cells of P. aeruginosa did not reduce this bacterial growth despite high levels of specific IgG. The results confirm the failure of peritoneal defences to clear an infection in the presence of an implant following either challenge with planktonic bacteria or insertion of a pre-colonised device, and demonstrate the rapid development of bacterial biofilms on the surface of the implant which appear to protect the bacteria from host defences, even when primed by pre-immunisation.

Animals↗

PubMed1992

An evaluation of single-room maternity care.

Patients appreciated the opportunity to give feedback. Nurses felt they were doing a good job and also that the decision to move into SRMC had been the right one. This project also highlighted for the nursing community the benefits for nursing practice that can result when representatives from education and service collaborate in research and evaluation.

Attitude of Health Personnel↗

PubMed1991

An in vivo model to study the pathobiology of infectious biofilms on biomaterial surfaces.

This study examines the morphology, ultrastructure, and microbiology of the intact biofilm developing on an implant surface. Silastic subdermal implant material was colonized with P. aeruginosa and surgically inserted into the peritoneal cavity of adult rabbits. After 4, 8, 28, and 42 days implants were recovered and the intact biofilms examined. P. aeruginosa colonized the implant throughout the entire experimental time. Microcolonies of glycocalyx-coated bacteria were observed within the biofilm. However, the bulk of the biofilm was host-generated and typically contained phagocytes trapped within a thick mesh of fibrin. Polymorphonuclear neutrophils were the predominant cell type. Isolated erythrocytes, macrophages, and fibroblasts were also observed. By day 28, the biofilm was enclosed in a fibrous capsule of vascularized connective tissue. The low numbers of neutrophils seen in biofilms from sterile Silastic sheets implanted into control animals suggested that neutrophilia may represent a specific cellular response to the bacterial colonization. The results indicate that the cell-mediated immune response provides for most of the biofilm mass on colonized implant surfaces. Inactivated phagocytes trapped in fibrin may "wall-off" the embedded bacterial microcolonies and thus shield them from live phagocytic leucocytes. Such a mechanism may play an important role in the pathogenesis of prosthetic device infections.

Animals↗

PubMed1991

Growth, activities of enzymes in the small intestine, and ultrastructure of microvillous border in gerbils infected with Giardia duodenalis.

The aim of this study was to assess and correlate changes in weight gain, food intake, small intestinal disaccharidase activities and microvillous border surface area over the course of a primary Giardia duodenalis infection in weanling Mongolian gerbils (Meriones unguiculatus). Weight gain in infected animals was significantly impaired between days 8 and 20 postinoculation when compared to age- and weight-matched controls. No difference in food intake was observed between groups. Trophozoite population in the small intestine was maximal on day 4 and 6 of infection, and colonization persisted in the duodenum throughout the experiment (30 days). In infected gerbils, mucosal sucrase and maltase activities were significantly depressed in the duodenum and jejunum on day 4 and in all areas of the small intestine by day 6. Eight and 25 days postinoculation, disaccharidase activities had recovered in the jejunum and distal small intestine but remained depressed in the duodenum, the area where trophozoite colonization persisted. Diffuse loss of microvillous border surface area was observed in the duodenum and jejunum after 6 days of infection. Eight days postinoculation, microvillus surface area had returned to normal in the jejunum, but not in the duodenum. Our findings demonstrate that acute giardiasis in weanling gerbils impairs weight gain, depresses disaccharidase activities, and diffusely reduces mucosal microvillous border surface area.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Demonstration of transient bacterobilia by foreign body implantation in feline biliary tract.

The biliary tract of cats is known to be free of autochthonous bacteria above the sphincter of Oddi. In this experiment we investigated whether transient bacterobilia occurs in the biliary system under normal conditions. Polyethylene tubes and human cholesterol stones were implanted surgically into the gallbladder of cats. Sham cholecystostomy was performed as control operation. These cats were euthanized at two, six, and 12 weeks, and the implants were removed, cultured, and studied by scanning electron microscopy (SEM). Cultures and SEM also were undertaken for material scraped from the mucosal surface of the biliary tract from these animals. Colonization of bacteria on the polyethylene tubes and the gallstones was found six and 12 weeks after implantation. Adherent bacterial biofilms were demonstrated on the surfaces of these implants. This experiment showed that transient bacterobilia exists in the feline biliary tract. The foreign body implants have facilitated the adhesion of planktonic bacteria in the bile onto their surfaces and have initiated the formation of adherent biofilms within which these bacteria persisted until the system was sampled.

Acinetobacter↗

PubMed1991

Rat model of experimental bacterial prostatitis.

A reproducible rat model of chronic bacterial prostatitis was developed employing a defined bacterial pathogen to study the pathophysiology of acute and chronic bacterial prostatitis. The progression of inflammation and its consequences following the retrograde introduction of bacteria through the acute and finally the chronic stages of prostatitis can be documented with microbiological, histological, ultrastructural and immunologic data. This model has many striking similarities to the natural history of human chronic bacterial prostatitis and further microbiological, antimicrobial and immune modulation or manipulation of this model should help us to further delineate the pathogenic mechanisms involved in this chronic infective disease.

Animals↗

PubMed1991

In vivo expression of iron regulated outer-membrane proteins in Pasteurella haemolytica-A1.

Pasteurella haemolytica-A1 was grown in vitro under iron-rich conditions, iron-depleted conditions, and in vivo within a chamber implanted in the peritoneal cavity of a rabbit to determine if iron regulated outer-membrane proteins were expressed in vivo. The antigenicity of outer membrane (OM) proteins from bacteria grown under these conditions was assessed by immunoblotting with pooled serum from convalescent bovine calves experimentally infected with P. haemolytica-A1 and serum from the implanted rabbit. Pasteurella haemolytica-A1 grown under iron-depleted conditions showed three distinct OM protein bands (71, 77, and 100 kDa) that were present in much lesser amounts when the organism was grown under iron-rich conditions. These same three bands were evident in OM protein preparations from bacteria grown in vivo. Western blotting indicated that these protein bands were recognized immunologically by the convalescent bovine serum and by serum from the implanted rabbit, in cells grown under the iron-depleted conditions and in vivo, but not if the bacteria were grown under the in vitro iron-rich conditions.

Animals↗

PubMed1991

Determination of the coefficient of kinetic friction of urinary catheter materials.

The coefficient of kinetic friction plays an important role in the biocompatibility of urinary catheters. A method for determination of the in vivo coefficient of kinetic friction is described that allows the comparison of the catheter-urethral interaction of the various materials used in the production of urinary catheters and the different types of lubricants.

Animals↗

PubMed1991

Bacteriologically stressed animal model of new closed catheter drainage system with microbicidal outlet tube.

We have used a catheterized rabbit model to test a newly developed catheter drainage system that incorporates a microbicidal outlet tube. In these tests, this new system was compared with a currently marketed closed drainage system, with daily challenge at the outlet tube using an auxotrophically marked uropathogenic strain of Escherichia coli. In the control series (silicone catheter connected to a standard drainage bag via a tamper-evidence seal) the challenge organism developed upstream biofilm colonization of the luminal surfaces of the catheter and drainage system that was complete in 4.6 +/- 2.1 days in 11 animals, while in 1 animal a rapid overgrowth of the system with Streptococcus faecalis developed. The presence of organisms other than the marked E. coli strain on the luminal surfaces of these control catheters showed that down stream colonization was also operative. In the test catheter drainage series, the microbicidal outlet tube insert precluded upstream colonization by the challenge organism in 12 of 16 catheters and significantly delayed (7.2 +/- 1.0 days) this colonization in the remaining 4 animals. When upstream colonization by exogenous bacteria was precluded by this effective device, downstream colonization of the drainage system by mixed populations of bacteria that probably migrated into the bladder via the extraluminal urethral route developed in some animals (6 of 16).

Animals↗

PubMed1991

Characterization of Tn5-Induced Mutants of Xenorhabdus nematophilus ATCC 19061.

A negative-selection vector, pHX1, was constructed for use in transposon mutagenesis of Xenorhabdus nematophilus ATCC 19061. pHX1 contains the Bacillus subtilis levansucrase gene which confers sucrose sensitivity. In addition, various Tn5-containing plasmids with different replication origins were transferred by conjugation from Escherichia coli into X. nematophilus ATCC 19061, and one of these plasmids, pGS9, yields Tn5 insertion mutants of X. nematophilus ATCC 19061. By using these two delivery vehicles, more than 250 putative Tn5 insertion mutants of X. nematophilus ATCC 19061 were isolated and were then characterized. Mutants that were altered in bromothymol blue adsorption, ability to lyse sheep erythrocytes, production of antibiotics on a variety of media, and virulence for Galleria mellonella were found.

Journal Article↗

PubMed1991

Metaphor and psychotherapy.

The authors describe the role of metaphor in the theory and practice of psychotherapy. Metaphors are considered fundamental elements of our worlds of language and concepts and not just figures of speech, poetic devices, parables, or creative ways to make interpretations. Metaphors shape the process of therapy by structuring the therapist's perceptions, stance, and attitude. They also organize the way problems are discussed as well as the solution that are seen as effective. The authors review the literature on metaphor in psychotherapy and explore common psychotherapeutic metaphors such as "psychotherapy is war," "the mind is a brittle object," "the conduit metaphor," and a variety of somatic metaphors. They conclude with a discussion of how metaphors function in the process of psychotherapy.

Humans↗