Search Results

You are looking at 41 - 50 of 58 items for

  • Author or Editor: C. Wayne McIlwraith x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract

Objective—To evaluate the effect of fibrin concentrations on mesenchymal stem cell (MSC) migration out of autologous and commercial fibrin hydrogels.

Sample—Blood and bone marrow from six 2- to 4-year-old horses.

Procedures—Autologous fibrinogen was precipitated from plasma and solubilized into a concentrated solution. Mesenchymal stem cells were resuspended in fibrinogen solutions containing 100%, 75%, 50%, and 25% of the fibrinogen precipitate solution. Fibrin hydrogels were created by mixing the fibrinogen solutions with MSCs and thrombin on tissue culture plates. After incubation for 24 hours in cell culture medium, the MSCs that had migrated onto the tissue culture surface and beyond the boundary of the hydrogels were counted. This procedure was repeated with a commercial fibrin sealant.

Results—Hydrogel-to-surface MSC migration was detected for all fibrin hydrogels. Migration from the 25% autologous hydrogels was 7.3-, 5.2-, and 4.6-fold higher than migration from 100%, 75%, and 50% autologous hydrogels, respectively. The number of migrating cells from 100%, 75%, and 50% autologous hydrogels did not differ significantly. With commercial fibrin sealant, the highest magnitude of migration was from the 25% hydrogels, and it was 26-fold higher than migration from 100% hydrogels. The 75% and 50% hydrogels resulted in migration that was 9.5- and 4.2-fold higher than migration from the 100% hydrogels, respectively.

Conclusions and Clinical Relevance—MSC migration from fibrin hydrogels increased with dilution of the fibrinogen component for both autologous and commercial sources. These data supported the feasibility of using diluted fibrin hydrogels for rapid delivery of MSCs to the surface of damaged tissues.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To measure passive spinal movements induced during dorsoventral mobilization and evaluate effects of induced pain and spinal manipulative therapy (SMT) on passive vertebral mobility in standing horses.

Animals—10 healthy adult horses.

Procedures—Baseline vertical displacements, applied force, stiffness, and frequency of the oscillations were measured during dorsoventral spinal mobilization at 5 thoracolumbar intervertebral sites. As a model for back pain, fixation pins were temporarily implanted into the dorsal spinous processes of adjacent vertebrae at 2 of the intervertebral sites. Vertebral variables were recorded again after pin placement and treadmill locomotion. In a random-ized crossover study, horses were allocated to control and treatment interventions, separated by a 7-day washout period.The SMT consisted of high-velocity, low-amplitude thrusts applied to the 3 non–pin-placement sites. Control horses received no treatment.

Results—The amplitudes of vertical displacement increased from cranial to caudal in the thoracolumbar portion of the vertebral column. Pin implantation caused no immediate changes at adjacent intervertebral sites, but treadmill exercise caused reductions in most variables. The SMT induced a 15% increase in displacement and a 20% increase in applied force, compared with control measurements.

Conclusions and Clinical Relevance—The passive vertical mobility of the trunk varied from cranial to caudal. At most sites, SMT increased the amplitudes of dorsoventral displacement and applied force, indicative of increased vertebral flexibility and increased tolerance to pressure in the thoracolumbar portion of the vertebral column.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the use of a combination of avocado and soybean unsaponifiable (ASU) extracts for the treatment of experimentally induced osteoarthritis in horses.

Animals—16 horses.

Procedures—Osteoarthritis was induced via osteochondral fragmentation in 1 middle carpal joint of each horse; the other joint underwent a sham operation. Horses were randomly allocated to receive oral treatment with ASU extracts (1:2 [avocado-to-soybean] ratio mixed in 6 mL of molasses; n = 8) or molasses (6 mL) alone (placebo treatment; 8) once daily from days 0 to 70. Lameness, response to joint flexion, synovial effusion, gross and histologic joint assessments, and serum and synovial fluid biochemical data were compared between treatment groups to identify effects of treatment.

Results—Osteochondral fragmentation induced significant increases in various variables indicative of joint pain and disease. Treatment with ASU extracts did not have an effect on signs of pain or lameness; however, there was a significant reduction in severity of articular cartilage erosion and synovial hemorrhage (assessed grossly) and significant increase in articular cartilage glycosaminoglycan synthesis, compared with placebo-treated horses.

Conclusions and Clinical Relevance—Although treatment with ASU extracts did not decrease clinical signs of pain in horses with experimentally induced osteoarthritis, there did appear to be a disease-modifying effect of treatment, compared with findings in placebotreated horses. These objective data support the use of ASU extracts as a disease-modifying treatment for management of osteoarthritis in horses.

Full access
in American Journal of Veterinary Research

Abstract

Objectives—To establish reference mechanical nociceptive threshold (MNT) values of the equine thoracic limb and to assess the use of MNT values to detect pain associated with induced osteoarthritis in the middle carpal joint.

Animals—24 adult horses.

Procedures—MNT values were evoked by a pressure algometer at 17 sites within each thoracic limb during 2 baseline sessions conducted an average of 5 days apart. Effects of age, sex, weight, and wither height on MNT values were assessed separately for each site. Tolerance of horses to the procedure was graded subjectively and correlated with MNT values. Synovitis and osteoarthritis were induced arthroscopically in the middle carpal joint of 1 randomly selected thoracic limb. The opposite limb served as a sham-operated control limb. Mechanical nociceptive threshold values were recorded weekly and correlated with clinical, radiographic, and necropsy scores measured over 10 weeks. Lower MNT values corresponded with increased pain, whereas higher MNT values indicated reduced pain.

Results—A gradual increase in MNT values was detected from proximal-to-distal sites of the thoracic limbs. High MNT values were recorded for geldings and tall horses. In general, tolerance to procedure scores was positively correlated with overall pooled MNT values within each thoracic limb. From 2 to 6 weeks after surgery, the osteoarthritic limb had significantly reduced MNT values within the carpal region. The osteoarthritic limb also had significant changes in clinical examination, radiographic, and necropsy scores, which were poorly correlated with MNT values.

Conclusions and Clinical Relevance—Pressure algometry provided objective assessment of nociception of the thoracic limb; however, MNT values were poorly correlated with clinical variables used to assess osteoarthritis.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine intralimb orientation changes with an inertial measurement unit (IMU) in hooves of horses at a walk and trot after induction of weight-bearing single forelimb lameness and to determine whether hoof orientations are similar to baseline values following perineural anesthesia.

Animals—6 clinically normal horses.

Procedures—3-D hoof orientations were determined with an IMU mounted on the right forelimb hoof during baseline conditions, during 3 grades of lameness (induced by application of pressure to the sole), and after perineural anesthesia. Linear acceleration profiles were used to segment the stride into hoof breakover, stance, initial swing, terminal swing, and total swing phases. Intralimb data comparisons were made for each stride segment. A repeated-measures mixed-model ANOVA was used for data analysis.

Results—Lameness resulted in significant changes in hoof orientation in all planes of rotation. A significant increase in external rotation and abduction and a significant decrease in sagittal plane rotation of the hoof were detected at hoof breakover during lameness conditions. For sagittal plane orientation data, the SDs determined following perineural anesthesia were higher than the SDs for baseline and lameness conditions.

Conclusions and Clinical Relevance—Results of this study indicated the IMU could be used to detect 3-D hoof orientation changes following induction of mild lameness at a walk and trot. An increase in data variability for a sagittal orientation may be useful for assessment of local anesthesia for hooves. The IMU should be further evaluated for use in clinical evaluation of forelimb lameness in horses.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To assess whether the combination of hyaluronan, sodium chondroitin sul-fate, and N-acetyl-d-glucosamine (HCSG) lubricates articular cartilage in vitro and modulates joint lubrication in vivo.

ANIMALS

16 healthy adult horses.

PROCEDURES

The effects of HCSG injections on SF lubricant properties and joint health, immediately after injury and 2 weeks later, were analyzed by use an equine osteochondral fracture model of post-traumatic osteoarthritis (OA). Middle carpal joints of adult horses were randomly assigned to 1 of 4 surgical treatment groups as follows: normal nonsurgical group (n = 8), normal sham-surgical group (8), OA-induced surgical group with HCSG injection (8), or OA-induced surgical group with saline (0.9% NaCl) solution injection (8). Synovial fluid was aspirated periodically and analyzed for boundary lubrication function and lubricant molecules. At 17 days, joints were screened for gross pathological changes.

RESULTS

Induction of OA led to an impairment of SF lubrication function and diminished hyaluronan concentration in a time-dependent manner following surgery, with HCSG injection lessening these effects. Certain friction coefficients approached those of unaffected normal equine SF. Induction of OA also caused synovial hemorrhage at 17 days, which was lower in joints treated with HCSG.

CONCLUSIONS AND CLINICAL RELEVANCE

After induction of OA, equine SF lubricant function was impaired. Hyaluronan-sodium chondroitin sulfate–N-acetyl-d-glucosamine injection restored lubricant properties at certain time points and reduced pathological joint changes.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To compare regional proportions and spatial distributions of volumetric bone mineral density (BMDv) of the palmar aspect of the distal epiphysis of the third metacarpal bone (McIII) in limbs with or without a condylar fracture from Thoroughbred racehorses.

SAMPLE McIIIs from cadavers of Thoroughbred racehorses with (n = 6 bones) and without (8) a condylar fracture.

PROCEDURES BMDv and spatial distributions of BMDv in peripheral quantitative CT images of the distal epiphysis of McIIIs were quantitatively assessed with spatial analysis software. Relative proportions of voxels within 9 threshold categories of BMDv and spatial statistics for BMDv distribution were compared between fractured and nonfractured limbs.

RESULTS No significant differences in BMDv characteristics were identified between fractured and nonfractured limbs, although fractured limbs had a lower proportion of voxels in the BMDv thresholds 700 to < 800 mg/cm3 and 800 to < 900 mg/cm3 but a higher proportion of voxels in the BMDv threshold 1,000 to < 1,100 mg/cm3 for the central condylar region of the medial condyle. Results of spatial analysis reflected the response of bone to race training rather than differences between fractured and nonfractured limbs. In both limb groups, uniform clusters of low BMDv with areas of high BMDv were identified.

CONCLUSIONS AND CLINICAL RELEVANCE BMDv characteristics of the distal epiphysis of McIII reflected training load, and fracture characteristics were subtle. Serial imaging techniques in conjunction with detailed training data are required to elucidate the onset of the pathological response to load in horses.

Full access
in American Journal of Veterinary Research

Abstract

Objective

To determine whether serum or synovial fluid concentrations of chondroitin sulfate epitope 846 and carboxy propeptides of type II collagen (CPII) can be used to diagnose osteochondral fragmentation (OC) in horses.

Animals

38 horses with unilateral OC of the radiocarpal (n = 31) or intercarpal (33) joints and 8 clinically and radiographically normal horses.

Procedures

For horses with OC, serum and synovial fluid concentrations of epitope 846, CPII, and keratan sulfate (KS) were determined, along with synovial fluid WBC counts and total protein concentrations. Serum epitope 846, CPII, and KS concentrations were measured in control horses.

Results

Synovial fluid epitope 846 and total protein concentrations were significantly higher in the joints with OC than in unaffected joints, but CPII and KS concentrations and WBC counts were not. Synovial fluid total protein and 846 epitope concentrations were linearly related to grade of OC. Serum epitope 846 and CPII concentrations were significantly higher in horses with OC than in control horses. Discriminant analysis allowed 27 of 34 (79%) horses to be correctly classified as having or not having OC on the basis of serum epitope 846 and CPII concentrations.

Conclusions

Results suggest that serum and synovial fluid concentrations of epitope 846 and CPII are associated with OC. Increases in concentrations of epitope 846 and CPII suggest that increased synthesis of cartilage aggrecan and type II procollagen may be associated with OC.

Clinical Relevance

Measurement of serum epitope 846 and CPII concentrations may be useful in the diagnosis of OC in horses. (Am J Vet Res 1999;60:306–309)

Free access
in American Journal of Veterinary Research

Summary

Using biodegradable pins, sternal cartilage autografts were fixed into osteochondral defects of the distal radial carpal bone in ten 2 to 3-year-old horses. The defects measured 1 cm2 at the surface and were 4 mm deep. Control osteochondral defects of contralateral carpi were not grafted. After confinement for 7 weeks, horses were walked 1 hour daily on a walker for an additional 9 weeks. Horses were euthanatized at 16 weeks. Half of the repair tissue was processed for histologic and histochemical (H&E and safranin-O fast green) examinations. The other half was used for the following biochemical analyses: type-I and type-II collagen contents, total glycosaminoglycan content, and galactosamine-to-glucosamine ratio. On histologic examination, the repair tissue in the grafted defects consisted of hyaline-like cartilage. Repair tissue in the nongrafted defects consisted of fibrocartilaginous tissue, with fibrous tissue in surface layers. On biochemical analysis, repair tissue of grafted defects was composed predominantly of type-II collagen; repair tissue of nongrafted defects was composed of type-I collagen. Total glycosaminoglycan content of repair tissue of grafted defects was similar to that of normal articular cartilage. Total glycosaminoglycan content of nongrafted defects was 62% of that of normal articular cartilage (P < 0.05). Repair tissue of all defects was characterized by galactosamine-to-glucosamine ratio significantly (P < 0.05) higher than that of normal articular cartilage. These results at 16 weeks after grafting indicate that sternal cartilage may potentially constitute a suitable substitute for articular cartilage in large osteochondral defects of horses.

Free access
in American Journal of Veterinary Research

Summary

The effects of intra-articular administration of methylprednisolone acetate (mpa) on the healing of full-thickness osteochondral defects and on normal cartilage were evaluated in 8 horses. In group-1 horses (n = 4), a 1-cm-diameter, full-thickness defect was created bilaterally in the articular cartilage on the dorsal distal surface of the radial carpal bone. Cartilage defects were not created in group-2 horses (n = 4). One middle carpal joint was randomly selected in each horse (groups 1 and 2), and treated with an intra-articular injection of 100 mg of mpa, once a week for 4 treatments. Injections began 1 week after surgery in group-1 horses. The contralateral middle carpal joint received intra-articular injections of an equivalent volume of 0.9% sodium chloride solution (scs), and served as a control. Horses were evaluated for 16 weeks, then were euthanatized, and the middle carpal joints were examined and photographed. Synovial and articular cartilage specimens were obtained for histologic and histochemical evaluation.

Gross morphometric evaluation of the healing defects in group-1 horses revealed that 48.6% of the defect in control joints and 0% of the defect in mpa-treated joints was resurfaced with a smooth, white tissue, histologically confirmed as fibrocartilage. This replacement tissue was a firmly attached fibrocartilage in control joints and a thin fibrous tissue in mpa-treated joints. The articular cartilage in joints treated with mpa had morphologic changes, including chondrocyte cluster formation, loss of palisading architecture, and cellular necrosis in both groups of horses. Histochemical (safranin-0) staining intensity was reduced significantly (P < 0.05) in all layers of articular cartilage in mpa-treated joints in groups 1 and 2. In the replacement tissue, intense safranin-0 staining was found only in the chondrocyte clusters deep in the tissue of control joints, confirming fibrocartilage repair. Intra-articular administration of mpa in this dosing regimen thus induced degenerative changes in normal articular cartilage and resulted in histomorphologic changes in the repair of full-thickness articular osteochondral defects in horses.

Free access
in American Journal of Veterinary Research