Biomedical subjects

Jo Ann C Eurell

Publications and source records attributed to Jo Ann C Eurell.

9 recordsLinked to original sources

PubMed2006

The mechanical properties and osteoconductivity of hydroxyapatite bone scaffolds with multi-scale porosity.

The relative osteoconductivity and the change in the mechanical properties of hydroxyapatite (HA) scaffolds with multi-scale porosity were compared to scaffolds with a single pore size. Non-microporous (NMP) scaffolds contained only macroporosity (250-350 microm) and microporous (MP) scaffolds contained both macroporosity and microporosity (2-8 microm). Recombinant human bone morphogenetic protein-2 (rhBMP-2) was incorporated into all scaffolds via gelatin microspheres prior to implantation into the latissimus dorsi muscle of Yorkshire pigs. After 8 weeks, only the MP scaffolds contained bone. The result demonstrates the efficacy of the MP scaffolds as drug carriers. Implanted and as-fabricated scaffolds were compared using histology, microcomputed tomography, scanning electron microscopy, and compression testing. Implanted scaffolds exhibited a stress-strain response similar to that of cancellous bone with strengths between those of cancellous and cortical bone. The strength and stiffness of implanted NMP scaffolds decreased by 15% and 46%, respectively. Implanted MP scaffolds lost 30% of their strength and 31% of their stiffness. Bone arrested crack propagation effectively in MP scaffolds. The change in mechanical behavior is discussed and the study demonstrates the importance of scaffold microporosity on bone ingrowth and on the mechanical behavior of HA implant materials.

Animals↗

PubMed2006

Bone response to 3D periodic hydroxyapatite scaffolds with and without tailored microporosity to deliver bone morphogenetic protein 2.

Three types of model hydroxyapatite (HA) scaffolds were implanted in the metacarpal and metatarsal bones of goats. Scaffolds, consisting of a latticed pattern of rods, were fabricated with a solid freeform fabrication (SFF) technique. All scaffolds contained macropores; some were also fabricated with micropores (5.2 +/- 2.0 microm). Recombinant human bone morphogenetic protein-2 (rhBMP-2) was added to some microporous scaffolds. rhBMP-2 caused increased percent filled with bone tissue compared to microporous scaffolds without rhBMP-2. Lamellar bone in the scaffolds was aligned perpendicular to the long axis of the bone near the junctions of the rods that make up the scaffold but was more random away from the junctions of rods. Microporous scaffolds stained beneath areas of contact with new bone. This staining might indicate either extracellular matrix (ECM) in the rods, byproducts of ECM production, or reaction of cellular products with the scaffold.

Animals↗

PubMed2005

Dens invaginatus of the mandibular first molars in a dog.

A 6-year-old dog was presented for draining tracts associated with both mandibular first molar teeth. Radiographs of the affected teeth showed periapical bone lysis. Surgical tooth extractions were performed and the tooth segments were submitted for histopathologic examination. Microscopic evaluation of the teeth showed in folding of the enamel and dentin consistent with a diagnosis of dens invaginatus. Examination performed 13-months following the extraction procedures indicated uncomplicated healing at the extraction sites and no other visible evidence of endodontic disease.

Animals↗

PubMed2005

Evaluation of an osteoconductive resorbable calcium phosphate cement and polymethylmethacrylate for augmentation of orthopedic screws in the pelvis of canine cadavers.

OBJECTIVE: To evaluate the effect of an osteoconductive resorbable calcium phosphate cement (CPC) on the holding power of bone screws in canine pelvises and to compare the effect with that for polymethylmethacrylate (PMMA). SAMPLE POPULATION: 35 pelvises obtained from canine cadavers. PROCEDURE: Each pelvis was sectioned longitudinally. Within each pair of hemipelvises, one 4.0-mm cancellous screw was placed in the sacroiliac (SI) region and another in the iliac body. Similar regions on the contralateral-matched hemipelvis were assigned 1 of 3 augmentation techniques (CPC-augmented 4.0-mm cancellous screws, PMMA-augmented 4.0-mm cancellous screws, and CPC-augmented 3.5-mm cortical screws). Pullout force was compared between matched screws and between treatment groups prior to examination of cross sections for evaluation of cement filling and noncortical bone-to-cortical bone ratio. RESULTS: CPC and PMMA augmentation significantly increased pullout force of 4.0-mm screws inserted in the SI region by 19.5% and 33.2%, respectively, and CPC augmentation significantly increased pullout force of 4.0-mm cancellous screws inserted in the iliac body by 21.2%. There was no difference in the mean percentage augmentation between treatment groups at either location. Cement filling was superior in noncortical bone, compared with filling for cortical bone. Noncortical bone-to-cortical bone ratio was significantly greater in the sacrum (6.1:1) than the ilium (1.3:1). CONCLUSIONS AND CLINICAL RELEVANCE: CPC and PMMA improve the ex vivo holding strength of 4.0-mm cancellous screws in the SI and iliac body regions and SI region, respectively. Cement augmentation may be more effective in areas with greater noncortical bone-to-cortical bone ratios.

Absorptiometry, Photon↗

PubMed2005

Effects of sodium hyaluronate and methylprednisolone acetate on proteoglycan synthesis in equine articular cartilage explants.

OBJECTIVE: To determine effects of sodium hyaluronate (HA) on corticosteroid-induced cartilage matrix catabolism in equine articular cartilage explants. SAMPLE POPULATION: 30 articular cartilage explants from fetlock joints of 5 adult horses without joint disease. PROCEDURE: Articular cartilage explants were treated with control medium or medium containing methylprednisolone acetate (MPA; 0.05, 0.5, or 5.0 mg/mL), HA (0.1, 1.0, or 1.5 mg/mL), or both. Proteoglycan (PG) synthesis was measured by incorporation of sulfur 35-labeled sodium sulphate into PGs, and PG degradation was measured by release of radiolabeled PGs into the medium. Total glycosaminoglycan (GAG) content in media and explants and total explant DNA were determined. RESULTS: Methylprednisolone acetate caused a decrease in PG synthesis, whereas HA had no effect. Only the combination of MPA at a concentration of 0.05 mg/mL and HA at a concentration of 1.0 mg/mL increased PG synthesis, compared with control explants. Methylprednisolone acetate increased degradation of newly synthesized PGs into the medium, compared with control explants, and HA alone had no effect. Hyaluronate had no effect on MPA-induced PG degradation and release into media. Neither MPA alone nor HA alone had an effect on total cartilage GAG content. Methylprednisolone acetate caused an increase in release of GAG into the medium at 48 and 72 hours after treatment. In combination, HA had no protective effect on MPA-induced GAG release into the medium. Total cartilage DNA content was not affected by treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Our results indicate that HA addition has little effect on corticosteroid-induced cartilage matrix PG catabolism in articular cartilage explants.

Animals↗

PubMed2005

Tablet computers in the veterinary curriculum.

Tablet computers offer a new method of information management in veterinary medical education. With the tablet computer, students can annotate class notes using electronic ink, search for keywords, and convert handwriting to text as needed. Additional electronic learning resources, such as medical dictionaries and electronic textbooks, can be readily available. Eleven first-year veterinary students purchased tablet computers and participated in an investigation of their working methods and perceptions of the tablet computer as an educational tool. Most students found the technology useful. The small size and portability of the tablet allowed easy transport and use in a variety of environments. Most students adapted to electronic notetaking by the second week of classes; negative experiences with the tablet centered on a failure to become comfortable with taking notes and navigating on the computer as opposed to writing and searching on paper. A few performance-related problems, including short battery life, were reported. Tablet software allowed conversion of faculty course notes from a variety of original formats, meaning that instructors could maintain their original methods of note preparation. Adopting a consistent naming convention for files helped students to locate the files on their computers, and smaller file sizes helped with computer performance. Collaboration between students was fostered by tablet use, which offers possibilities for future development of collaborative learning environments.

Attitude to Computers↗

PubMed2004

Effects of phenylbutazone, indomethacin, prostaglandin E2, butyrate, and glutamine on restitution of oxidant-injured right dorsal colon of horses in vitro.

OBJECTIVE: To study the effects of phenylbutazone, indomethacin, prostaglandin E2 (PGE2), glutamine, and butyrate on restitution of oxidant-injured right dorsal colon of horses in vitro. SAMPLE POPULATION: Right dorsal colon from 9 adult horses euthanatized for reasons other than gastrointestinal tract disease. PROCEDURES: Mucosal segments from the right dorsal colon were injured via exposure to HOCl and incubated in Ussing chambers in solutions containing phenylbutazone, indomethacin, indomethacin and PGE2, glutamine, and butyrate. Transepithelial resistance and mucosal permeability to mannitol were measured, and all mucosal segments were examined histologically. RESULTS: The HOCl-injured mucosa had lower resistance and higher permeability to mannitol, compared with control tissue. Histologic changes were also evident. Resistance of HOCl-injured mucosa recovered partially during the incubation period, and glutamine improved recovery. Phenylbutazone and indomethacin increased resistance, but these increases were not significant. Butyrate and PGE2 had no effects, compared with nontreated HOCl-injured tissues. Mucosal permeability to mannitol was lower in glutamine-treated tissue, compared with nontreated tissue. Histologic changes reflected the resistance and permeability changes. CONCLUSIONS AND CLINICAL RELEVANCE: According to our findings, phenylbutazone and indomethacin do not seem to interfere with restitution of oxidant-injured mucosa of equine colon in vitro, and glutamine could facilitate mucosal restitution.

Analysis of Variance↗

PubMed2003

Effects of acetylcysteine and migration of resident eosinophils in an in vitro model of mucosal injury and restitution in equine right dorsal colon.

OBJECTIVES: To evaluate the in vitro protective effects of acetylcysteine and response of resident mucosal eosinophils in oxidant-induced injury to tissues of right dorsal colon of horses. ANIMALS: 9 adult horses. PROCEDURE: Gastrointestinal mucosa was damaged in vitro with 3 mM hypochlorous acid (HOCl), with and without prior exposure to 6mM acetylcysteine. Control tissues were not exposed to HOCl or acetylcysteine. Control and damaged tissues were incubated in Krebs-Ringer-bicarbonate solution and tissue resistance measured during 240 minutes. Tissue permeability to radiolabeled mannitol was also used to assess mucosal barrier integrity. Tissues were examined by light microscopy before and after HOCl exposure and during and after incubation. RESULTS: Exposure to HOCl caused tissue damage and decreased tissue resistance. Restitution did occur during the incubation period. Eosinophils were located near the muscularis mucosae in freshly harvested tissues and migrated towards the luminal surface in response to HOCl-induced injury. Compared with tissues treated with HOCl without acetylcysteine, pretreatment with acetylcysteine prevented HOCl-induced tissue damage, changes in resistance, and histologically detectable eosinophil migration. The permeability to mannitol increased to the same extent in tissues treated with HOCl alone or with acetylcysteine and HOCl. CONCLUSIONS AND CLINICAL RELEVANCE: Eosinophils migrated toward the mucosal surface in equine colon in response to oxidant-induced damage in vitro. This novel finding could be relevant to inflammation in equine colon and a pathophysiologic feature of many colonic diseases. Acetylcysteine protected the mucosa against oxidant-induced injury and may be useful as a treatment option for various gastrointestinal tract disorders in horses.

Acetylcysteine↗

PubMed2002

Effect of cisplatin on bone transport osteogenesis in dogs.

OBJECTIVE: To document effects of cisplatin on regenerate bone formation during the distraction and consolidation phases of bone transport osteogenesis. ANIMALS: 10 skeletally mature hounds. PROCEDURES: Bone transport osteogenesis was performed to reconstruct a 3-cm defect in the radius of each dog. Five dogs were randomly selected to receive cisplatin (70 mg/m2, IV, q 21 d for 4 cycles), and 5 were administered saline (0.9% NaCl) solution. Bone mineral density was measured by use of dual-energy x-ray absorptiometry (DEXA) on days 24, 55, and 90 after surgery. Dogs were euthanatized 90 days after surgery. Histomorphometry was performed on nondecalcified sections of regenerate bone. Bone mineral density and histomorphometric indices of newly formed bone were compared between groups. RESULTS: Densitometric differences in regenerate bone mineral density were not detected between groups at any time period. Cisplatin-treated dogs had decreased mineralized bone volume, decreased percentage of woven bone volume, decreased percentage of osteoblast-covered bone, increased porosity, and increased percentage of osteoblast-covered surfaces, compared with values for control dogs. Lamellar bone volume and osteoid volume did not differ significantly between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Regenerate bone will form and remodel during administration of cisplatin. Results of histomorphometric analysis suggest that bone formation and resorption may be uncoupled in cisplatin-treated regenerate bone as a result of increased osteoclast activity or delayed secondary bone formation during remodeling. These histomorphometric differences were modest in magnitude and did not result in clinically observable complications or decreased bone mineral density as measured by use of DEXA.

Absorptiometry, Photon↗