Polysulphated Glycosaminoglycan Research Articles

Does the intra-articular injection of antimicrobials alongside corticosteroids or other medications reduce the risk of synovial sepsis?

PICO question
 In horses, does treatment with intra-articular antimicrobials concurrently with intra-articular corticosteroids reduce the risk of iatrogenic synovial sepsis compared to intra-articular corticosteroids alone?
 Clinical bottom line
 From the current literature, there is no evidence showing that intra-articular injection of antibiotics in conjunction with corticosteroids reduces the risk of synovial sepsis. However, the intra-articular injection of polysulphated glycosaminoglycans (PSGAGs) in combination with corticosteroids was noted as a risk factor for developing iatrogenic synovial sepsis and therefore concurrent antibiotic injection when administering PSGAGs may be warranted. The reported frequency of infection following intra-articular injections was very low (0.02–0.08%). An overall prevalence of iatrogenic synovial sepsis following all intra-articular injections based on data from all included studies was calculated as 0.02% (CI 0.02–0.03%). However, due to the paucity of literature on the topic, further studies are required in this field to determine more accurate clinical recommendations.

Synovial sepsis is rare following intrasynovial medication in equine ambulatory practice.

There are few observational studies regarding the potentially serious complication of synovial sepsis following intrasynovial medication in general equine practice. Quantification of risk is fundamental to fully inform decision-making and owner consent prior to undertaking procedures. To describe the occurrence of synovial sepsis following intrasynovial injections in a large ambulatory equine practice between 2006-2011. Retrospective cohort study. Medication records were cross-referenced against synovial cytology submissions and hospital admissions for synovial sepsis. The occurrence of synovial sepsis within strata of interest, including horse age, sex and product used were described as proportions with corresponding 95% confidence intervals, and measures of attributable risks. In the study period, 9456 intrasynovial medications were performed in 4331 sessions. The most frequently used medications were: corticosteroids (3869/4331, 89.3% [95% CI 88.4, 90.3%]), hyaluronate (3617/4331, 83.5% [95% CI 82.4, 84.6%]) and amikacin sulphate (4044/4331, 93.4% [95% CI 92.6, 94.1%]). Overall four horses developed post medication synovial sepsis (0.04% [95% CI 0.0, 0.08%] of all medications), two of these cases were given polysulphated glycosaminoglycans and hyaluronate (2/14, 14.3% [95% CI 0.0, 32.6%]), two were given triamcinolone acetonide (2/3592, 0.1% [95% CI 0.0, 0.1%]), and hyaluronate (2/3617, 0.06% [95% CI 0.0, 0.1%]). One of these cases had received concurrent medication with amikacin sulphate (1/4044, 0.02% [95% CI 0.0, 0.1%]). All four cases returned to racing following joint lavage. Due to the low frequency of cases multivariable statistical analysis was not performed. Although the study was conducted in an ambulatory setting, the population included a high number of racehorses, limiting application to the general horse population. The frequency of synovial sepsis in this population of horses was 0.04%. These data may be helpful in informing clients regarding the potential risks of adverse complications resulting from intrasynovial medication.

The effects of pentosan polysulphate and polysulphated glycosaminoglycan on chondrogenic differentiation of canine bone marrow-derived mesenchymal stem cells in three-dimensional alginate cultures

The effects of pentosan polysulphate and polysulphated glycosaminoglycan on chondrogenic differentiation of canine bone marrow-derived mesenchymal stem cells in three-dimensional alginate cultures

Risks of Synovial Sepsis Following Intrasynovial Medication in Ambulatory Practice, 2006–2011: 9456 Intrasynovial Injections

AimsTo determine the incidence of synovial sepsis following intra‐articular and intrathecal injections. Synovial sepsis is a serious potential complication of intrasynovial medication.MethodsAvailable case records for all horses receiving intrasynovial medications (ISMs) performed by 9 ambulatory clinicians were examined over 5 years (2006–2011). Intrasynovial medications were defined as therapeutic interventions, based on clinical history and orthopaedic examination; nontherapeutic injections for diagnostic analgesia were excluded. Routine protocol was not to clip injection sites; the skin was prepared using standard aseptic technique. Scrupulous aseptic injection technique was employed at all times. All horses were under the care of a single practice, dealing with mainly Thoroughbred racehorses. Records were cross‐referenced against synovial cytology submissions and hospital admissions for synovial sepsis. Development of 2 out of 4 clinicopathological signs of synovial sepsis (lameness, joint distension, synovial white blood cell count >10,000/l, synovial total protein >25 g/l) within 8 weeks of medication of the same synovial space was considered to represent a post medication complication (PMC). Failure of the PMC to resolve with conservative therapy was considered to represent post medication synovial sepsis (PMSS).ResultsDuring the study period 9456 ISMs were recorded, in 4332 sessions, in 1732 horses. Corticosteroids were included in 92.3% of ISMs, 94.8% included amikacin and 0.15% (14/9456) included polysulphated glycosaminoglycans (PSGAGs). Twelve horses developed PMC (0.0013% ISM), 4 horses developed PMSS (0.0004% ISM). All 4 horses returned to use following joint lavage. Administration of intrasynovial PSGAGs, was significantly associated with PMSS (P<0.0001 OR = 787 95% CI 145–20,337). Intrasynovial medications that included amikacin were less likely to develop PSSM (P = 0.005 OR = 0.0181 95% CI 0.0019–0.174); however if the PSGAGs group was excluded the difference became nonsignificant (P = 0.0981).Conclusions and practical significanceThe risk of iatrogenic sepsis following intrasynovial medication is extremely low. Intrasynovial medication with PSGAGs should be avoided without concomitant antimicrobials.AcknowledgementsA. Wilson and K. Batteate for case collation.Ethical animal researchNot required by this Congress: retrospective analysis of case records. Sources of funding: None. Competing interests: None.

Autologous bone marrow mesenchymal stromal cells for regeneration of injured equine ligaments and tendons: A clinical report

The use of Mesenchymal Stromal Cells (MSCs) in orthopedic practice has recently and rapidly acquired an important role. Therapies based on the use of MSCs for the treatment of acute injuries as well as chronic inflammatory disorders are gradually becoming clinical routine. These cells have demonstrated intriguing therapeutic potentialities (i.e.: inflammation control, tissue regeneration and pathological scar prevention), that have been taken into consideration for use in both human and veterinary medicine. In particular, horses represent high performance athletes considered models for human pathologies since musculo-skeletal disorders frequently occur in this species. In the past, repair of tendon injures were performed by different methods. In particular, clinical therapy was based on ice application, bandage, box rest and controlled exercise. An alternative approach consisted on the use of corticosteroid (inflammation reduction) and other drugs (sodium hyaluronate, polysulphated glycosaminoglycans, beta aminoproprionitrile fumarate). Furthermore, surgical treatments like accessory ligament desmotomy, local irritation by line firing or pin firing were commonly used. More recently ultrasound, laser therapy, electromagnetic field therapy have been considered. Unfortunately, they did not allow complete tissue healing and quite often animals did not regain competitiveness. In order to minimize this inconvenience, the use of MSCs has been introduced as an alternative to the traditional approach since it represents a potential tool to improve tissue regeneration.Aim of this study was to evaluate the capability of MSCs to improve the functional outcome of horses affected by tendonitis and desmitis. Thirty-three breed and activity-matched horses affected by tendonitis or desmitis, were included in clinical trial scored for lesions and subdivided into two groups. Group 1 animals were treated with autologous MSCs, associated with platelet rich plasma (group 1). Bone marrow samples were collected from the sternum of the treated horses and processed in order to isolate MSCs. Following cell therapy, they were subjected to a rehabilitation period and their ability to resume training was evaluated. In this study, implanted MSCs caused no adverse reactions and thirteen out of the eighteen inoculated horses returned to race competitions. On the contrary, no improvement was seen in the twelve animals of group 2 treated with pin firing, that were not able to resume sport activity. In conclusion the clinical trial proves the safety of equine bone-marrow derived MSCs and a successful outcome of the treated animals that returned to their previous level of sport activity.

Adult Rat Bones Maintain Distinct Regionalized Expression of Markers Associated with Their Development

The incidence of limb bone fracture and subsequent morbidity and mortality due to excessive bone loss is increasing in the progressively ageing populations of both men and women. In contrast to bone loss in the weight-bearing limb, bone mass in the protective skull vault is maintained. One explanation for this could be anatomically diverse bone matrix characteristics generated by heterogeneous osteoblast populations. We have tested the hypothesis that adult bones demonstrate site-specific characteristics, and report differences at the organ, cell and transcriptome levels. Limb bones contain greater amounts of polysulphated glycosaminoglycan stained with Alcian Blue and have significantly higher osteocyte densities than skull bone. Site-specific patterns persist in cultured adult bone-derived cells both phenotypically (proliferation rate, response to estrogen and cell volumes), and at the level of specific gene expression (collagen triple helix repeat containing 1, reelin and ras-like and estrogen-regulated growth inhibitor). Based on genome-wide mRNA expression and cluster analysis, we demonstrate that bones and cultured adult bone-derived cells segregate according to site of derivation. We also find the differential expression of genes associated with embryological development (Skull: Zic, Dlx, Irx, Twist1 and Cart1; Limb: Hox, Shox2, and Tbx genes) in both adult bones and isolated adult bone-derived cells. Together, these site-specific differences support the view that, analogous to different muscle types (cardiac, smooth and skeletal), skull and limb bones represent separate classes of bone. We assign these differences, not to mode of primary ossification, but to the embryological cell lineage; the basis and implications of this division are discussed.

Response of a Collagenase-Induced Tendon Injury to Treatment with a Polysulphated Glycosaminoglycan (Adequan)

This study explored the hypothesis that local administration of a polysulphated glycosaminoglycan (PSGAG) in the early phase of healing of a standard collagenase-induced tendon injury in the superficial digital flexor tendon of the rabbit would reduce the degenerative effects of inflammatory mediators and proteases and preserve normal tendon morphology, composition, and biomechanical properties. Histological and ultrastructural changes together with the mechanical properties, dry weight, collagen content, and amount of DNA in healing tissue at the site of the lesion were assessed in treated and untreated animals. In treated lesions 28 days after injury, the normal orientation of tenoblasts and collagen fibrils was well preserved compared with the disorganized scar formation seen in untreated animals. The degree of cellularity was significantly higher in the untreated lesions. At the ultrastructural level the collagen in the healing tissue of the treated animals consisted of a mixture of small diameter, new regenerated fibrils intermingled with well-preserved large diameter, old fibrils, aligned to the long axis of the tendon; in untreated animals small, randomly arranged new fibrils predominated. The diameters of treated tendons had returned to normal, but in untreated animals the injured tendons remained significantly thicker than their controls. The percentage dry weight and collagen contents of treated injured tendons approximated those of control normal tendons, whereas those of untreated tendons were significantly less than those of the control values. The DNA content of injured treated tendons was not significantly different from that of normal contralateral controls, while in the untreated tendons it was significantly higher. There were no significant differences between the normal and the contralateral treated injured tendons in ultimate strength, fatigue strength, stiffness, and maximum absorbed energy. However in the untreated animals, although the tendon diameter was significantly greater, the ultimate strength, fatigue strength, stiffness, and maximum absorbed energy were significantly lower than the contralateral control. These data suggest that polysulphated glycosaminoglycans are effective in restoring the morphological, biochemical, and biomechanical properties of injured soft connective tissues and may be of clinical value in the treatment of acute tendon injury.

Multivariable analysis of factors influencing outcome of 2 treatment protocols in 128 cases of horses responding positively to intra‐articular analgesia of the distal interphalangeal joint

There is limited knowledge available of factors influencing response to treatments of the DIP-joint in horses with lameness responding to diagnostic analgesia of the DIP-joint. For this reason a multivariable statistical analysis was performed. Horses with lameness reduced by > or = 75% 10 min after intra-articular analgesia of the DIP-joint, can be treated successfully by intra-articular medication of the joint. Multiple factors influence the response to treatment. The study was performed retrospectively based on clinical records of horses treated with either polysulphated glycosaminoglycan (PSGAG) or methylprednisolone acetate (MPA) in the DIP-joint between January 1996 and January 2003. Information was collected from clinical records and from the owners of the horses via a detailed questionnaire, in which they described their perception of the outcome a minimum of one year after treatment. Allocation of the horses to the 2 treatment groups was done mainly because of a change in treatment policy. In Regime A all horses received 3 intra-articular injections of PSGAG approximately 8 days apart, whereas in Regime B all horses received a single intra-articular injection of MPA as a first treatment. If the horse did not improve sufficiently to return to work by 4 weeks, a series of 3 intra-articular PSGAG injections was administered. Of the horses receiving Regime A, 67% had a successful outcome, compared with 46% of the group receiving Regime B. A significantly better result was obtained in dressage horses than in jumping horses (eventing and showjumping). Other variables such as age, duration of lameness, distribution of lameness, degree of lameness, response to DIP-joint analgesia and radiographic observations were also associated with success of treatment. There is a rationale for using either PSGAG or MPA intra-articularly in the treatment of lameness, reduced > or = 75% within 10 min of analgesia of the DIP-joint.

Osteoarthritis of the talocalcaneal joint in 18 horses

Talocalcaneal osteoarthritis (TO) is an uncommon cause of moderate to severe hindlimb lameness, on which only isolated case reports have been published to date. To review the clinical features of TO and determine optimal methods for diagnosis, management and prognosis. The case records from 4 referral centres of 18 horses showing hindlimb lameness considered, as a result of clinical investigation, to be caused by TO, were reviewed. TO affected mature sports and pleasure horses (age 7-16 years) and caused moderate to severe lameness, usually of sudden onset with no obvious inciting cause. There were few localising signs, other than worsening of lameness by hock flexion. Tarsocrural joint analgesia produced improvement in lameness in 6/11 horses (55%) and perineural analgesia of the tibial and fibular nerves complete soundness in 6/14 horses (43%) in which it was performed; 7/14 horses (50%) showed a further substantial improvement. Radiological findings included subchondral bone lysis and sclerosis and irregular joint space width, seen most obviously in a lateromedial view. Nuclear scintigraphy revealed marked uptake of radiopharmaceutical predominantly plantaromedially in the region of the talus in the 7 horses in which it was performed. Fourteen horses were treated conservatively with box- or pasture-rest, with or without intra-articular corticosteroids, hyaluronic acid or polysulphated glycosaminoglycan, and all remained lame. Intra-articular corticosteroids appeared to have no effect in any horse. Of 10 horses receiving conservative management only, 6 were subjected to euthanasia, 3 were retired and 1 remained in light work, but was still lame. Two horses treated by either partial tibial and fibular neurectomy or subchondral forage failed to regain soundness and were retired. Six horses were treated by surgical arthrodesis of the talocalcaneal joint with 2 or three 5.5 mm AO screws introduced obliquely across the joint from the plantarolateral aspect of the calcaneus, which resulted in improvement in lameness in all cases. Osteoarthritis of the talocalcaneal joint causes acute onset severe lameness, but clinical findings and diagnostic analgesia often fail to identify precisely the site of pain. Consistent radiographic changes suggested TO was contributing to the lameness and this diagnosis was supported by nuclear scintigraphy. The poor success of conservative treatment (including intra-articular medication) suggests that surgical arthrodesis is the treatment of choice, although the prognosis is still poor for a return to full soundness. The clinical features described should facilitate more accurate diagnosis and prognosis. A novel surgical treatment is described which appears to offer significant improvement in the lameness. Further work is necessary to determine the causes of this condition and more effective management.

Intralesional polysulphated glycosaminoglycan as treatment of equine collagenase induced tendinitis: clinical, ultrasonographic and histopathologic evaluation

The effect of intratendineous injections of polysulphated glycosaminoglycan (PSGAG) as treatment of collagenase-induced tendonitis was studied. Two groups (GI and GII) of five Arabian horses each, males and females, two to six year-old, were submitted to experimental tendinitis of the superficial digital flexor tendon of the left thoracic limb by intratendineous injection of 1.0ml of collagenase (2.5mg/ml). Seven days after the induced-lesions were created, the horses of GI received five intralesional injections of 1.0ml (125mg) of PSGAG, every four days. Horses of GII received injections of saline in the same dose and rate. Clinical and ultrasonographic evaluations were performed periodically, during 150 days. All animals showed lameness, increased local pain, heat and swelling 24 hours after the injury was created. All signs, except to swelling, which remained visible by the end of the study, showed regression in all animals. Lesions of variable size, shape and position were evidenced by the ultrasonographic evaluation, reaching maximum severity between the seventh and the 23rd days. By the end of the study, the echogenicity grade ranged from 1 to 2, and the grade of fiber alignment from 0 to 2. The histopathologic analysis demonstrated repair areas with intense fibroplasia and neovascularization, collagen fibers poorly organized, and thickened hypercellular endotenon. The data of this study did not show significant differences between the treated and control groups, therefore leading to the conclusion that the intralesional injection of PSGAG did not have beneficial effects in the treatment of collagenase-induced tendinitis.

Polysulphated glycosaminoglycans modulate transcription of interleukin-1β treated chondrocytes in monolayer culture

SummaryThe ability of polysulphated glycosaminoglycans (PSGAGs, Adequan®) to modulate the transcription of major articular cartilage matrix proteins and enzymes was examined. Northern blot analyses were used to compare steady-state mRNA levels of type-II procollagen, aggrecan core protein, matrix metalloproteinase (MMP)-1, MMP-3, tissue inhibitor of metalloproteinase (TIMP)-1, and TIMP-3 in equine chondrocytes grown in monolayer culture. The groups included: control, low-dose (0.1mg/ml) Adequan®, high-dose (1.0mg/ml) Adequan®, IL-1 β (10ng/ml), IL-1 β with low-dose Adequan®, and IL-1 β with high-dose Adequan®. The responses (p<0.05) to treatment were compared with one-way analysis of variance and post hoc least significant difference test. Interleukin-1 β significantly decreased steady-state levels of type-II procollagen (0.5x) and aggrecan core protein (to undetectable levels) and significantly increased MMP-1 (11.7x), MMP-3 (1.8x), TIMP-1 (1.9x), and TIMP-3 (5.1 x). Adequan® alone significantly increased steady-state mRNA levels of type-II procollagen (1.6x) and decreased MMP-1 (0.3x at high-dose only), MMP-3 (0.5x), and TIMP-1 (0.3x at high-dose only). In IL-1 β-treated chondrocytes, Adequan® significantly increased steady-state mRNA levels of type-II procollagen (1.4x of IL-1 β-treated levels), aggrecan core protein (IL-1 β -treated had no detectable expression), and MMP-3 (3.6 x at high dose) and significantly decreased steady-state mRNA levels of MMP-1 (0.3 x), and TIMP-1 (0.2x). This study is the first to demonstrate that Adequan® alters steady-state mRNA levels of key matrix proteins and enzymes; that it counteracts some of the deleterious effects of IL-1 β; and that these effects are in part dose-dependent.

Effects of anti-arthritic drugs on proteoglycan synthesis by equine cartilage.

The concentration-effect relationships of phenylbutazone, indomethacin, betamethasone, pentosan polysulphate (PPS) and polysulphated glycosaminoglycan (PSGAG), on proteoglycan synthesis by equine cultured chondrocytes grown in monolayers, and articular cartilage explants were measured. The effect of PSGAG on interleukin-1beta induced suppression of proteogycan synthesis was also investigated. Proteoglycan synthesis was measured by scintillation assay of radiolabelled sulphate (35SO4) incorporation. Polysulphated glycosaminoglycan and PPS stimulated proteoglycan synthesis in chondrocyte monolayers in a concentration-related manner with maximal effects being achieved at a concentration of 10 microg/mL. Polysulphated glycosaminoglycan reversed the concentration-related suppression of proteoglycan synthesis induced by interleukin-1beta. Neither PSGAG nor PPS exerted significant effects on radiolabel incorporation in cartilage explants. Betamethasone suppressed proteoglycan synthesis by both chondrocytes and explants at high concentrations (0.1-100 microg/mL), but the effect was not concentration-related. At low concentrations (0.001-0.05 microg/mL) betamethasone neither increased nor decreased proteoglycan synthesis. Phenylbutazone and indomethacin increased radiolabel incorporation in chondrocyte cultures but not in cartilage explants at low (0.1, 1 and 10 microg/mL), but not at high (20 and 100 microg/mL) concentrations. These findings may be relevant to the clinical use of these drugs in the treatment of equine disease.

Polysulphated glycosaminoglycan treatments can mitigate decreases in stiffness of articular cartilage in a traumatized animal joint.

A single, blunt impact to the rabbit patellofemoral joint has been shown to decrease the stiffness of retropatellar cartilage and increase the thickness of the underlying bone. Polysulphated glycosaminoglycan treatments, on the other hand, have been shown to inhibit the degradation of articular cartilage and possibly increase synthesis of collagen and glycosaminoglycans in experimental studies on diseased joints. The aim of the current study was to examine the effect of early treatments with polysulphated glycosaminoglycans on cartilage using an in vivo post-trauma animal model. The study used 24 Flemish Giant rabbits in three groups: control, impacted, and impacted with treatment. Treatment consisted of intramuscular injections the day of insult and every 4 days thereafter for 6 weeks. At 30 weeks after trauma, mechanical tests were performed on the retropatellar cartilage to determine its mechanical stiffness. The patellae were also grossly evaluated for surface lesions on the retropatellar cartilage and histologically processed to measure the thickness of the subchondral bone. The rabbits that received no treatment had a statistically significant decrease in stiffness (modulus) for the cartilage of the impacted patellae compared with that of the contralateral, unimpacted patellae and compared with the cartilage of rabbits in the control group. The degradation in mechanical stiffness, however, was not observed in patellae of rabbits in the group receiving treatment. There was also a significant increase in the underlying thickness of the subchondral plate on the impacted patellae compared with that on the contralateral, unimpacted sides for rabbits in both the treated and nontreated groups. In conclusion, the polysulphated glycosaminoglycan treatments minimized a decrease in mechanical stiffness (modulus) of retropatellar articular cartilage 30 weeks after trauma. The mechanism by which the mechanical stiffness of the cartilage was preserved is unknown.

The Effects of Polysulphated Glycosaminoglycan on the Healing of Collagenase Induced Tendinitis

Summary Objective. To examine the effects of polysulphated glycosaminoglycan on tendon healing in a controlled collagenase injury model. Design. The study used a completely randomized design with four horses assigned to each of two groups, control and treated. The superficial digital flexor tendons from each horse were measured weekly by ultrasound techniques. The differences between groups were evaluated using t-statistics and trends summarized by simple linear regression. Animals. Eight horses (four Thoroughbreds and four Standardbreds) with normal superficial flexor tendons were divided into two groups of four. Group #1 control horses were not treated. Group #2 horses were treated with polysulphated glycosaminoglycans. Procedure. All of the horses had tendinitis induced in the superficial flexor tendon of both forelimbs by the injection of 4000 IU of collagenase. The treated group received 500 mg of polysulphated glycosaminoglycan (PSGAG) IM every five days for seven treatments beginning 24 h after injection of collagenase. The control group received saline at the same time periods. Ultrasound examination of each limb was performed on days 1, 3, 5, and 7 post-injection and weekly thereafter for eight weeks. An image analysis system was used to measure the proportion of tendon area damaged in mm2 on the recorded images, and these values were plotted over time. The horses were euthanatized at eight weeks and histological evaluation was performed on longitudinal sections of excised tendons. Results. The size of the tendon core defects created by the collagenase enzyme, represented as the proportion of area damaged, decreased significantly faster in the treatment group (ρ <0.01). Histologic evaluation of the core defects confirmed what was seen sonographically. Conclusion. Polysulphated glycosaminoglycans had a positive effect on tendon healing in a collagenase induced tendinitis model. Clinical relevance. Polysulphated glycosaminoglycans may be beneficial in managing clinical cases of tendinitis.Eight horses had experimental core defects induced in the superficial digital flexor tendon of both forelimbs. One group of four horses received PSGAG IM every 5 days for seven treatments. The control group received saline. The core defects in the PSGAG treatment group developed echogenic ultrasound patterns earlier, and the mean ratio of area of the tendon decreased significantly faster in the treatment group.

The effect of drugs commonly used in the treatment of equine articular disorders on the activity of equine matrix metalloproteinase-2 and 9.

Loss of articular cartilage, which is the most important pathological lesion occurring in osteoarthritis, has been shown to be enzymatically mediated. The matrix metalloproteinases (MMPs) are a group of enzymes which have been implicated in this degradation of articular cartilage matrix. The use of pharmacological agents to inhibit this catabolic process in the joint is a potential route for therapeutic intervention. The gelatinase MMPs, MMPs-2 and 9, were purified by affinity chromatography from equine cell cultures. The ability of phenylbutazone, flunixin, betamethasone, dexamethasone, methylprednisolone acetate (MPA), hyaluronan, pentosan polysulphate and polysulphated glycosaminoglycan (PSGAG) to inhibit equine MMPs-2 and 9 were assessed by two degradation assays. Whilst some agents did have direct effects on MMP activity, these effects were only obtained at concentrations which were unlikely to be achieved for any length of time in vivo. It is improbable that any pharmacological agent, currently used in the horse, has a significant effect on gelatinase MMP activity.

The Effect of Polysulphated Glycosaminoglycan on the Production of Proteoglycan by Equine Tendon Fibroblasts in Monolayer Culture

SummaryEquine tendon fibroblasts were isolated from tissue fragments of superficial digital flexor tendon, subcultured and maintained in monolayers. The cells were treated with two dosage regimes of polysulphated glycosaminoglycan (PSGAG). The high dose group received 0,25, 50 or 200 μg/ml of PSGAG and the low dose group received 0,0.3,1 or 2 μg/ml of PSGAG. Proteoglycan production was measured via liquid scintillation counting, following radiolabel with 35SO4 (40 μCi/ml). The counts were measured in both the cell associated fraction and the supernatant fraction.The addition of PSGAG to the culture system did not adversely affect cell viability at any treatment level. The cells in all of treatment groups produced measurable amounts of proteoglycan in both the cell associated and supernatant fractions. There were not any differences between the treatment means in any of the four groups (high dose cell-associated, high dose supernatant, low dose cell-associated, low dose supernatant). A linear trend in proteoglycan production was not documented between treatment groups in either the cell-associated or the supernatant fractions for either of the two dosage regimes. The significance of the lack of effect is equivocal. PSGAG may influence tendon healing in a manner other than by increasing proteoglycan production.The effect of polysulphated glycosaminoglycan on the production of proteoglycans by equine tendon fibroblasts was investigated. A previously described model was utilized to grow the tendon fibroblasts in monolayer cultures. Significant treatment effects were not seen at either a high or low dose of PSGAG. Addition of the PSGAG did not adversely affect cell viability at any treatment level.

Treatment of acute superficial digital flexor tendon injury in horses with polysulphated glycosaminoglycan.

Horses with acute injuries of the superficial digital flexor tendon were treated with a course of seven intramuscular injections of 500 mg of polysulphated glycosaminoglycan at four-day intervals. Clinical assessments of the lesions were made by a veterinary surgeon at the time of each injection and 14 and 28 days after the last injection. A total of 150 courses of the drug were administered and adequately completed assessment forms were returned for 80 cases. Long-term follow-up data were obtained for 19 cases. The subjective assessments by the veterinary surgeons showed that in 80 per cent of cases the drug was felt to be of value in the treatment of acute tendon injury.

Heparin binding to platelet factor-4. An NMR and site-directed mutagenesis study: arginine residues are crucial for binding

Native platelet factor-4 (PF4) is an asymmetrically associated, homo-tetrameric protein (70 residues/subunit) known for binding polysulphated glycosaminoglycans like heparin. PF4 N-terminal chimeric mutant M2 (PF4-M2), on the other hand, forms symmetric tetramers [Mayo, Roongta, Ilyina, Milius, Barker, Quinlan, La Rosa and Daly (1995) Biochemistry 34, 11399-11409] making NMR studies with this 32 kDa protein tractable. PF4-M2, moreover, binds heparin with a similar affinity to that of native PF4. NMR data presented here indicate that heparin (9000 Da cut-off) binding to PF4-M2, while not perturbing the overall structure of the protein, does perturb specific side-chain proton resonances which map to spatially related residues within a ring of positively charged side chains on the surface of tetrameric PF4-M2. Contrary to PF4-heparin binding models which centre around C-terminal alpha-helix lysines, this study indicates that a loop containing Arg-20, Arg-22, His-23 and Thr-25, as well as Lys-46 and Arg-49, are even more affected by heparin binding. Site-directed mutagenesis and heparin binding data support these NMR findings by indicating that arginines more than C-terminal lysines, are crucial to the heparin binding process.

Influence of intra‐articular sodium hyaluronate and polysulphated glycosaminoglycans on the biochemical composition of equine articular surface repair tissue

The influence of repeated intra-articular injections of sodium hyaluronate and polysulphated glycosaminoglycan on the repair of full-thickness osteochondral defects was examined in the midcarpal joints of ponies. The study showed no significant difference between treated and control groups with regard to total collagen content, uronic acid content or the relative proportions of Type I and Type II collagen in the repair tissue, indicating that the drugs did not affect the biochemical composition of the repair tissue 11 weeks after defect induction.

A case of superficial digital flexor tendinitis: ultrasonographic examination and treatment with intralesional polysulphated glycosaminoglycans

A case of superficial digital flexor tendinitis: ultrasonographic examination and treatment with intralesional polysulphated glycosaminoglycans